- 


FIRST 'GLIMPSB  OF  THE  ELECTRIC  LIGHT. 


THE 


AGE  OF  ELECTRICITY 


From  Amber-Soul  to  Telephone 


BY 


PARK   BENJAMIN,   PH.D. 


Ariel  and  all  his  quality." 

The  Tempest. 


NEW  YORK 
CHARLES    SCRIBNER'S    SONS 

1889 


COPYRIGHT,  1886,  BY 
CHARLES   SCRIBNER'S  SONS. 


PRESS  OF  BERWICK  &  SMITH, 
BOSTON,  MASS. 


PREFACE. 


THIS  little  work  is  not  a  technical  treatise,  nor  is  it 
addressed  in  any  wise  to  the  professional  electrician.  It 
is  simply  an  effort  to  present  the  leading  principles  of 
electrical  science,  their  more  important  applications,  and 
of  these  last  the  stories,  in  a  plain  and,  it  is  hoped,  a 
readable  way.  There  are  no  formulas  in  the  book. 
Only  such  technical  terms  as  have  now  made  their  way 
into  every-day  use  are  employed ;  and  the  more  strictly 
scientific  branches  of  the  subject,  such  as  measurement, 
testing,  etc.,  are  omitted  altogether. 

It  is  a  singular  fact,  that  probably  not  an  electrical 
invention  of  major  importance  has  ever  been  made,  but 
that  the  honor  of  its  origin  has  been  claimed  by  more 
than  one  person.  There  was  a  dispute  over  the  Leyden- 
jar,  and  a  long  and  acrimonious,  controversy  about  the 
galvanic  battery.  Franklin's  discovery  of  the  identity 
of  lightning  and  electricity  is  still  claimed  for  French 
philosophers;  the  title  of  uthe  father  of  the  telegraph'* 
is  given  to  Wheatstone  in  England,  and  to  Morse  in  the 
United  States,  although  to  neither  of  these  inventors,  but 
to  Joseph  Henry,  the  lasting  gratitude  of  the  world  be- 


iii 


136 


iv  PEE  FACE. 

longs  ;  Dal  Negro,  McGawley,  Page,  and  Henry  have  all 
been  named  each  as  the  first  and  only  original  inventor 
of  the  electro-motor  ;  Davidson,  Davenport,  Lillie,  Jacobi, 
Page,  and  Hall  are  each  credited  with  the  invention  of 
the  electric  railway ;  Page  and  Ruhmkorff  dispute  the 
invention  of  the  induction  coil ;  Jordan  and  Spenser,  and 
others  beside,  waged  a  bitter  war  over  their  respective 
claims  to  the  discovery  of  the  electro-deposition  of 
metals.  Plaute,  as  the  inventor  of  the  secondary  bat- 
tery, becomes  deposed  by  the  prior  work  of  Ritter ; 
Gramme  finds  his  ring  armature  in  the  dynamo  antici- 
pated by  Pacinotti.  Professor  Hughes  had  no  sooner 
announced  his  microphone  than  Mr.  Edison  claimed  it. 
Hjorth,  Varley,  Siemens,  and  Wheatstone  share  the 
honor  of  originating  the  self-exciting  dynamo.  Contests 
are  still  in  existence  over  the  incandescent  electric  lamp, 
with  Edison  and  Swan  and  Sawyer  in  the  front.  And  as 
for  the  present  telephone  war,  —  the  greatest  conflict  of 
all,  —  this  is  fast  becoming  not  merely  a  question  of 
whether  Reis  or  Drawbaugh  or  Gray  or  Bell  or  Dolbear, 
or  any  other  of  the  numerous  claimants,  was  or  was  not 
the  inventor  of  the  electrical  transmission  of  speech,  but 
a  national  issue  involving  the  rights  of  the  people  against 
corporate  monopoly,  and  perhaps  also  in  some  degree  the 
integrity  of  our  patent  system. 

Where  it  has  been  necessary  to  deal  with  these  disputed 
matters,  the  author  has  endeavored  to  present  the  facts 
without  partisan  bias.  The  reader  will,  no  doubt,  notice 
that  the  names  of  many  electrical  inventors  now  celebrated 


PREFACE.  V 

are  not  mentioned,  or  but  briefly  referred  to.  This  is 
because  their  inventions  —  when  theirs  —  are  but  improve- 
ments in  details  remarkable  rather  for  quantity  than 
quality ;  or  else  require  descriptions  too  technical  for 
these  pages. 

For  the  most  part,  all  historical  data  have  been  gath- 
ered from  publications  contemporary  with  the  date  of  first 
production  of  the  several  discoveries  and  inventions,  and 
in  many  cases  from  the  original  writings  of  the  inventors 
and  discoverers  themselves.  As  for  sources  of  informa- 
tion in  general,  the  author  can  only  say  that  there  lie 
before  him,  at  this  writing,  the  first  book  on  electricity 
ever  written  in  the  English  language,  —  Robert  Boyle's 
modest  little  pamphlet  of  1675,  —  and  the  latest  numbers 
of  the  electrical  journals,  fresh  from  the  press ;  and  that 
he  has  ranged  throughout  the  whole  field  of  electrical 
literature  anywhere  and  everywhere,  in  the  most  arbitrary 
manner,  between  these  limits. 

In  a  few  instances,  however,  it  would  be  ungracious 
to  deny  special  credit :  and  therefore  acknowledgment  is 
made  for  aid  from  Prof.  S.  P.  Thomson's  excellent  "  Ele- 
mentary Lessons  in  Electricity  and  Magnetism,"  Mr.  J. 
H.Gordon's  ''Treatise  on  Electric  Lighting,"  Messrs. 
Preece  &  Sivewright's  "Telegraphy,"  and  Prof.  J.  T. 
Sprague's  latest  and  best  treatise  on  "  Electricity,"  among 
modern  works  ;  and  from  Dr.  Priestley's  grand  "History 
of  Electricity,"  among  those  of  the  last  century.  Free 
use  has  been  made  of  the  files  of  "The  Scientific  Amer- 
ican," of  "  The  Journal  of  the  Franklin  Institute,"  and 


vi  PREFACE. 

the  special  electrical  journals  of  this  country;  and  of 
those  of  "  Engineering "  and  "The  Mechanics'  Maga- 
zine," and  electrical  periodicals  abroad.  In  the  prepara- 
tion of  the  chapter  on  Telegraphy,  Mr.  Alfred  M.  A. 
Beale  has  rendered  valuable  assistance  ;  and  several  of 
the  engravings  in  the  chapter  on  Galvanic  Batteries  have 
been  kindly  supplied  by  Messrs.  John  Wiley  &  Sons,  from 
Niaudet's  work  on  that  subject. 

NEW  YORK,  May  15, 1886. 


CONTENTS. 


CHAPTER  PAGE 

I.    THE  MYTH  OF  THE  AMBER  SOUL     ....  1 
II.    THE     DISCOVERIES     OF     THE    EARLY     EXPERI- 
MENTERS    7 

III.  THE  CAGING  OF  THE  LIGHTNING     ....  15 

IV.  ELECTRICITY  IN  HARNESS 28 

V.    THE  GALVANIC  BATTERY,  AND  THE  CONVERSION 

OF     CHEMICAL     ENERGY     INTO     ELECTRICAL 

ENERGY 35 

VI.    THE  ELECTRO-MAGNET,  AND  THE  CONVERSION  OF 

ELECTRICITY  INTO  MAGNETISM    ....      68 
VII.    THE  DYNAMO-ELECTRIC  MACHINE,  AND  THE  CON- 
VERSION   OF    MAGNETISM    AND    MECHANICAL 
MOTION  INTO  ELECTRICITY 88 

VIII.    THE    ELECTRIC    LIGHT.  —  THE    CONVERSION    OF 

ELECTRICAL  ENERGY  INTO  HEAT  AND  LIGHT  .    118 
IX.    ELECTRO-MOTORS,  AND  THE  CONVERSION  OF  ELEC- 
TRICAL ENERGY  INTO  MECHANICAL  ENERGY    .    152 
X.    ELECTROLYSIS.  —  ELECTRO-METALLURGY  AND  THE 

STORAGE-BATTERY 182 

vU 


Vlll  CONTENTS. 

CHAPTEK  PAGE 

XI.    THE  ELECTRIC  TELEGRAPH 208 

XII.    THE  SPEAKING  TELEPHONE 272 

XIII.  THE  INDUCTION  COIL,  AND  POWERFUL  ELECTRIC 

DISCHARGES 325 

XIV.  THE  APPLICATIONS  OF  ELECTRICITY  TO  MEDICINE, 

WAR,  RAILWAYS,  TIME,  Music,  ETC.        .        ,    333 


THE  AGE  OF  ELECTRICITY. 


THE  AGE  OF  ELECTRICITY. 


CHAPTER   I. 

THE    MYTH    OF   THE    AMBER    SOUL. 

SOME  years  ago,  there  was  found  in  a  tomb  in  Egypt  an 
alabaster  vase,  the  sole  contents  of  which  were  a  few  dry, 
hard,  and  blackened  seeds.  These  the  discoverer  brought 
to  England,  and  planted  them  in  the  rich  loam  of  his 
garden,  more  from  curiosity  than  from  any  belief  that 
they  actually  would  germinate.  To  his  surprise,  in  due 
time  fresh  young  sprouts  appeared  which  grew  and  flour- 
ished ;  and  finally,  in  the  harvest  season,  ears  of  wheat, 
as  many  as  fifteen  or  twenty  from  a  single  stalk,  were 
gathered.  So  it  was  proved  that  despite  their  having 
been  sealed  in  the  ancient  tomb  for  nearly  three  thousand 
years,  the  seeds,  to  all  appearances  as  lifeless  as  the  huge 
stones  which  surrounded  them,  had  retained  all  their  vi- 
tality ;  and  we  might  imagine,  that  if,  during  these  many 
centuries,  wheat  had  disappeared  from  among  the  earth's 
products,  it  would  have  been  possible  in  time  from  these 
few  grains  to  cause  all  the  lands  again  to  teem  with  golden 
harvest. 

A  suggestive  parallel  exists  between  the  history  of  the 
wheat  kernel  shut  up  in  the  Egyptian  tomb,  and  that 

1 


2  THE  AGE   OF  ELECTRICITY. 

of  a  mere  atom  of  human  knowledge  which  for  nearly 
as  long  a  period  remained  as  unfruitful  and  buried  in 
the  minds  of  men.  Indeed,  among  all  the  wonders  of 
that  strangest  manifestation  of  the  energy  which  pervades 
all  nature,  and  which  we  call  electricity,  there  is  nothing 
more  remarkable  and  more  impressive  than  the  growth  of 
the  single,  simple,  and  uncoordinated  fact, — namely,  that 
amber,  when  rubbed,  behaves  in  a  curious  way,  —  into  the 
great  science  which  underlies  the  telegraph,  the  electric 
light,  and  the  telephone. 

How  rapid  this  growth  has  been,  is  within  the  remem- 
brance of  most  of  us.  Of  the  vastness  of  its  extent,  we 
have  on  all  sides  ocular  proof.  What  farther  progress 
may  be  made,  no  one  can  predict.  Conjecture  too  often 
outstrips  reason  :  impossibilities  and  impracticabilities  be- 
come confounded  ;  and  each  new  advance  only  reveals  a 
new  horizon,  beyond  which  who  knows  what  fields  may 
lie? 

There  is  a  familiar  old  Greek  legend,  which  tells  how 
Phaethon,  son  of  the  Sun,  once  rashly  undertook  to  drive 
his  father's  chariot  through  the  heavens.  As  the  story 
goes,  the  horses  despised  their  driver,  and  refused  to  be 
guided  by  him,  so  that  the  blazing  chariot  approached  too 
near  the  earth,  and  living  things  thereon  were  burned. 
Then  Jupiter,  very  wroth,  hurled  his  thunderbolt,  and 
killed  the  charioteer.  When  his  body,  which  fell  to  the 
earth,  was  found  by  his  sisters,  the  Heliades,  they  mourned 
long  and  bitterly,  until  at  last  the  Father  of  Gods,  pitying 
them,  changed  them  into  ever-sighing  poplars,  and  their 
tears  into  translucent  amber. 

And  so,  perhaps  because  of  this  legend,  the  Greeks 
looked  upon  amber  with  superstitious  reverence,  and  even 
thought  that  it  had  a  soul.  For  when  it  was  rubbed,  it 
seemed  to  live,  and  to  exercise  an  attraction  upon  other 


THE  MYTH  OF  THE  AMBEE   SOUL.  3 

things  distant  from  it.  They  likened  it  to  the  magnet ;  and 
yet  knew  it  to  be  different  from  the  loadstone,  for  in  the 
latter  the  property  of  drawing  other  things  to  itself  was 
inherent,  whereas  amber  could  only  be  brought  into  life  and 
activity.  It  was  easier  to  conceive  how  a  natural  body 
might  have  its  own  peculiar  properties,  however  incom- 
prehensible, —  just  as  a  tree  might  grow,  —than  to  ima- 
gine how  this  strange  substance,  at  one  time  inert,  could  be 
brought  to  life  by  the  same  process  which  would  restore 
vitality  to  a  limb  benumbed  by  cold.  Thus  they  specu- 
lated upon  an  amber  life,  and  an  amber  soul  as  its 
essence. 

In  the  light  of  our  modern  knowledge  we  might  perhaps 
trace  farther  the  chain  of  ancient  speculation.  Jupiter's 
thunderbolt  was  but  another  name  for  the  lightning-stroke, 
and  the  sequence  of  events  following  the  tragedy  resulted 
in  amber.  From  amber  we  can  reproduce  the  lightning  in 
miniature  ;  so  that  by  some  stretch  of  the  imagination 
we  might  suppose  that  the  Greeks  had  a  crude  concep- 
tion of  electrical  storage,  and  traced  the  manifestations 
derived  from  amber  to  imprisoned  lightning.  It  is  quite 
certain,  however,  that  those  who  were  initiated  in  the 
mystic  rites  of  the  ancients  clearly  understood  many  of 
the  principles  of  electricity  and  magnetism  which  have  been 
re-discovered  within  recent  years.  Professor  Schweigger 
considers  that  the  Vestal  fire  was  electrical,  and  points 
out  that  the  "twin  fires  from  the  electrical  spark  are 
sketched  in  a  very  natural  manner  in  the  representations 
of  Castor  and  Pollux  on  ancient  coins."  So  also  it  is 
believed  that  the  ancients  knew  of  the  therapeutic  effects 
of  electrical  currents,  and  the  polarity  of  electricity  and 
magnetism. 

Although  these  mysteries  were  jealously  guarded  from 
public  comprehension,  and  hence  all  knowledge  of  them 


4  THE  AGE   OF  ELECTRICITY. 

died  with  its  possessors,  Ennemoser  in  his  History  of 
Magic  says  that  "it  was  not  forbidden  to  make  known 
every  thing :  some  things  were  explained  to  the  uniniti- 
ated. For  instance,  the  uninitiated  were  made  acquainted 
with  amber,  and  with  its  property  when  rubbed."  We 
can  conjecture  that  the  uninitiated  were  thus  favored  be- 
cause in  any  event  they  would  be  reasonably  certain  to 
find  out  the  phenomenon  for  themselves.  Amber  was 
constantly  worn  as  an  amulet  and  in  jewellery ;  and  the 
friction  of  garments  would  produce  sufficient  excitation 
to  cause  it  to  attract  lint  or  other  fine  particles  which 
would  dim  its  lustre,  and  so  draw  the  wearer's  atten- 
tion. And  of  course,  inasmuch  as  explanations  natur- 
ally would  be  sought,  it  perhaps  suited  the  policy  of  the 
magi  to  attribute  the  fact  to  the  supernatural  qualities  of 
the  substance.  It  is  remarkable,  however,  to  note  that 
the  knowledge  of  the  electrical  properties  of  amber  sur- 
vived for  centuries,  doubtless,  because  the  whole  world  had 
it,  while  the  great  mass  of  facts  which  the  priests  and  magi 
collected  fell  into  utter  oblivion  ;  and  that  this  is  exactly 
the  reverse  of  the  conditions  under  which  the  great  bulk  of 
learning  which  was  handed  down  from  antiquity  through 
the  dark  ages  maintained  its  existence.  The  mediaeval 
monks  and  scholars  treasured  their  knowledge  of  natural 
science  while  dwelling  amid  rude  and  barbarous  peoples, 
in  order  that  it  might  be  handed  down  to  posterity.  The 
Greek  and  Egyptian  priests,  on  the  other  hand,  in  the 
midst  of  the  most  cultivated  peoples  that  had  ever  lived, 
surrounded  their  discoveries  with  every  sort  of  misleading 
myth,  until  finally  they  faded  into  oblivion. 

As  the  world  grew  older,  here  and  there  in  the  writings 
of  the  philosophers  reference  to  this  strange  property  of 
amber  appears.  Thales  (600  B.C.)  mentions  it,  and, 
being  the  earliest  writer  who  has  been  found  to  do  so,  is 


THE  MYTH  OF  THE  AMBER   SOUL.  5 

too  often  credited  with  the  discovery.  Some  three  hun- 
dred years  later  Theophrastus  notes  that  another  body, 
called  lyncurium,  —  supposed  to  be  either  tourmaline,  or 
the  hyacinth,  which  looks  like  amber, — acts  in  like  man- 
ner ;  and  Pliny  (B.C.  70)  refers  to  the  same. 

Then  there  is  a  great  gap  of  sixteen  centuries,  with 
hardly  a  published  word  to  show  that  all  had  not  been  for- 
gotten. Beckmann  quotes  from  an  edition  of  John  Sera- 
piou,  "  Lib.  de  simplicibus  medicinis,"  published  in  1531, 
a  reference  to  a  red  stone,  "  Hager  Albuzedi."  found  in 
the  East,  "  which  when  strongly  rubbed  against  the  hair  of 
the  head  attracts  chaff  as  the  magnet  does  iron  ; "  and  per- 
haps other  references  exist.  The  fact  however,  remained, 
and  was  supposed  to  be  peculiar  to  amber.  No  one 
attempted  to  explain  it.  The  superstition  of  the  amber 
soul  faded  and  was  forgotten.  The  phenomena  which 
Pliny  called  the  "awful  mysteries  of  nature"  puzzled 
men's  souls ;  yet  to  inquire  into  them  suggested  only 
impiety.  "  A  star,"  says  Seneca,  "settled  on  the  lance 
of  Gylippus  as  he  was  sailing  to  Syracuse  ;  and  spears 
have  seemed  to  be  on  fire  in  the  Roman  camp."  "About 
that  time,"  Caesar  records,  "  there  was  a  very  extraordinary 
appearance  in  the  army  of  Caesar.  In  the  mouth  of  Feb- 
ruary, about  the  second  watch  of  the  night,  there  suddenly 
arose  a  thick  cloud,  followed  by  a  shower  of  stones  ;  and 
the  same  night,  the  points  of  the  spears  belonging  to  the 
fifth  legion  seemed  to  take  fire."  Aristotle,  Pliny,  Oppian, 
and  Claudius  were  fully  acquainted  with  the  shocks  pro- 
duced by  the  torpedo.  Eustathius,  who  lived  in  the  fourth 
century  of  the  Christian  era,  says  that  a  freedman  of  Tibe- 
rius was  cured  of  the  gout  by  a  shock  from  this  fish  ;  the 
first-known  instance  of  the  application  of  electricity  to 
medical  purposes,  and  if  authentic  much  more  successful 
than  its  application  in  modern  times.  The  same  authority 


6  THE  AGE  OF  ELECTRICITY. 

asserts  that  Wolimer,  king  of  the  Goths,  was  able  to  emit 
sparks  from  his  body.  But  all  these  were  wonders  beyond 
human  ken  and  control.  The  whole  science  lay  in  the 
knowledge  of  the  single  fact,  that  excited  amber  attracted 
certain  light  bodies. 


DISCOVERIES   OF  EAELY  EXPERIMENTERS. 


CHAPTER    II. 

THE    DISCOVERIES    OF    THE    EARLY    EXPERIMENTERS. 

IN  the  year  1GOO  Dr.  William  Gilbert  of  London,  a 
surgeon  to  Queen  Elizabeth,  published  his  famous  work 
"  De  Magnete,"  and  then  made  known  that  the  attractive 
property  of  amber,  when  rubbed,  was  not  inherent  to  that 
substance,  but  existed  in  some  twenty  other  bodies,  such  as 
the  precious  stones,  glass,  sealing-wax,  sulphur,  and  resin. 
Inasmuch  as  these  all  acted  like  amber,  Gilbert  called 
them  electrics;  and  he  described  the  peculiar  phenomenon 
itself  as  electricity,  deriving  the  term  from  the  Greek 
word  for  amber,  elektron.  It  has  recently  been  pointed 
out,  that  the  Elektra  of  the  Homeric  legends  possesses 
certain  qualities  that  would  tend  to  suggest  that  she  is 
the  personification  of  lightning,  and  that  the  resemblance 
between  the  names  Elektra  and  elektron  cannot  be  ac- 
cidental. Whether,  however,  Gilbert  was  thus  antici- 
pated or  not,  is  immaterial.  The  publication  of  his  work 
marks  the  true  beginning  of  the  progress  of  the  science  ; 
and  its  immediate  effect  was  to  incite  philosophers  every- 
where to  efforts  to  extend  his  list  of  electrics. 

Singularly  enough,  this  remarkable  treatise  was  severely 
condemned  by  Bacon  in  the  "  Novum  Organum."  Not 
content  with  singling  it  out  for  citation  as  a  peculiarly 
striking  instance  of  inconclusive  reasoning,  and  of  truth 
distorted  by  "  preconceived  fancies/'  he  elsewhere  alludes 


8  THE  AGE   OF  ELECTRICITY. 

to  the  "  electric  energy  concerning  which  Gilbert  has  told 
so  many  fables."  A  century  and  a  half  later,  as  we  shall 
see,  these  "  fables  "  assumed  the  form  of  realities.  The 
sweeping  censure  of  so  high  an  authority  seems  to  have 
produced  its  natural  effect,  and  may  have  had  much  to  do 
in  materially  retarding  the  development  of  the  infant 
science. 

To  Gilbert's  category,  Cabaeus,  an  Italian  Jesuit,  added 
the  gums,  white  wax,  and  gypsum.  Then  Robert  Boyle 
got  the  first  glimpse  (it  was  no  more)  of  the  electric  light, 
by  noting  that  a  diamond  when  rubbed  became  luminous 
in  the  dark.  Then  Otto  von  Guericke,  burgomaster  of 
Magdeburg,  and  inventor  of  the  air-pump,  discovered  that 
electricity  was  manifested  by  repulsion  as  well  as  by  at- 
traction, and  that  a  globe  of  sulphur  after  attracting  a 
feather  repelled  the  same  until  the  feather  had  again  been 
placed  in  contact  with  some  other  substance. 

Guericke  contrived  an  apparatus  for  rotating  his  sulphur 
globe,  and  succeeded  in  obtaining  sparks  therefrom  ;  and 
that  was  the  real  genesis  of  the  electric  light.  By  this 
time  the  attention  of  the  scientific  world  was  aroused, 
and  other  philosophers  joined  in  the  investigation  of  the 
curious  phenomena.  Boyle,  then  contemporary  with  von 
Guericke,  proved  that  a  suspended  piece  of  rubbed  am- 
ber, which  attracted  other  bodies  to  itself,  was  in  turn 
attracted  by  a  body  brought  near  it ;  and  he  even  went 
so  far  as  to  maintain  that  an  electrified  body  threw  out 
an  invisible  glutinous  substance  which  laid  hold  of  light 
bodies,  and,  returning  to  the  source  from  which  it  ema- 
nated, carried  them  along  with  it.  Sir  Isaac  Newton,  by 
rubbing  a  flat  glass,  caused  light  bodies  to  jump  between 
it  and  the  table,  and  noticed  that  electric  attraction  was 
thus  transmitted  through  the  glass.  A  sea-captain  named 
Grofton  excited  the  dismay  of  mariners  by  asserting  that 


DISCOVERIES  OF  EARLY  EXPERIMENTERS.        9 

a  violent  thunder-storm  had  reversed  the  polarity  of  the 
compass-needles  aboard  his  vessel.  Dr.  Wall,  in  1708, 
made  experiments  with  large  pieces  of  amber  rubbed  by 
wool,  and  found  that  "  a  prodigious  number  of  little  crack- 
lings "  was  produced,  each  accompanied  by  a  flash  of  light. 
"  This  light  and  crackling,"  says  Dr.  Wall,  "  seem  in 
some  degree  to  represent  thunder  and  lightning." 

Probably  every  one  has  observed  the  peculiar  crackling 
which  follows  combing  of  the  hair  during  dry,  cold  weather, 
and  the  tendency  of  the  "  knotted  and  combined  locks  to 
part"  under  the  electrical  excitement  following  the  rub- 
bing of  the  comb. 

Robert  Boyle  appears  to  have  discovered  this  ;  and  he 
wrote  in  1G75  this  amusing  description  —  intended  to  be 
perfectly  serious  and  scientific  —  of  his  original  experi- 
ment on  "Locks  (false)  worn  by  two  very  Fair  Ladies 
that  you  know:"  "For  at  some  times  I  observed  that 
they  could  not  keep  their  Locks  from  flying  to  their  Cheeks 
and  (though  neither  of  them  made  any  use  or  had  any 
need  of  Painting)  from  sticking  there.  When  one  of  these 
Beauties  first  shew'd  me  this  Experiment,  I  turn'd  it  into 
a  Complemental  Raillery,  as  suspecting  there  might  be 
some  trick  in  it,  though  I  after  saw  the  same  thing  happen 
to  others  Locks  too.  But  as  she  is  no  ordinary  Virtuoso., 
she  very  ingeniously  remov'd  my  suspicions  and  (as  I  re- 
quested) gave  me  leave  to  satisfie  myself  further  by  desir- 
ing her  to  hold  her  warm  hand  at  a  convenient  distance 
from  one  of  these  Locks  taken  off  and  held  in  the  air.  For 
as  soon  as  she  did  this,  the  lower  end  of  the  Lock  which 
was  free  applied  itself  presently  to  her  hand  :  which  seemed 
the  most  strange  because  so  great  a  multitude  of  Hair 
would  not  have  been  easily  attracted  by  an  ordinary 
Electrical  Body." 

In  this  way,  for  more  than  a  hundred  and  twenty  years 


10  THE  AGE   OF  ELECTRICITY. 

after  the  publication  of  Gilbert's  work,  and  at  long  inter- 
vals, isolated  phenomena  were  observed,  and  a  fact  here 
and  there  gathered.  A  variety  of  curious  theories  had 
been  formulated.  Cabseus,  in  the  quaint  language  of 
Robert  Boyle,  "thinks  the  drawing  of  light  bodies  by 
Jet,  Amber,  etc.,  may  be  accounted  for  by  supposing  that 
the  steams  that  issue,  or  if  I  may  so  speak,  sally,  out  of 
Amber  when  heated  by  rubbing,  discuss  and  expell  the 
neighbouring  air  ; "  and  that  these  "  Electrical  Steams  .  .  . 
shrinking  back  swiftly  enough  to  the  Amber  do  in  their 
returns  bring  along  with  them  such  light  bodies  as  they 
meet  with  in  their  way."  Then  there  was  the  hypothesis 
"proposed  by  that  Ingenious  Gentleman  Sir  Kenelm  Digby, 
and  embraced  by  the  very  Learned  Dr.  Browne,"  that 
"  Rayes  or  Files  of  unctuous  steams  "  were  emitted,  which 
became  cooled  and  condensed,  and  so  "shrinking"  back, 
carried  light  bodies  with  them.  Newton  supposed  that 
the  excited  body  emitted  an  elastic  fluid  which  penetrated 
glass  ;  and  Gravesande  and  other  writers  maintained  that 
electricity  was  fire,  which,  being  inherent  to  all  bodies, 
became  manifest  by  friction. 

In  1720  Stephen  Gray,  a  Charterhouse  pensioner,  that 
"most  meritorious  philosopher"  as  Tyndall  calls  him, 
began  a  series  of  investigations  which  terminated  only 
when  he  died  sixteen  years  later. 

In  1729  Gray  experimented  with  a  glass  tube  stopped 
by  a  cork.  When  the  tube  was  rubbed,  the  cork  attracted 
light  bodies.  Gray  states  that  he  was  "much  surprised  " 
at  this,  and  he  "concluded  that  there  was  certainly  an 
attractive  virtue  communicated  to  the  cork."  "  This," 
says  Professor  Tyndall,  "  was  the  starting-point  of  our 
knowledge  of  electric  conduction  ; ' '  and  the  same  author- 
ity gives  the  following  account  of  Gray's  most  remarkable 
experiment :  — 


DISCOVERIES   OF  EARLY  EXPERIMENTERS.     11 

"He  suspended  a  long  hempen  line  horizontally  by 
loops  of  pack-thread,  but  failed  to  transmit  through  it  the 
electric  power.  He  then  suspended  it  by  loops  of  silk, 
and  succeeded  in  sending  the  '  attractive  virtue  '  through 
seven  hundred  and  sixty-five  feet  of  thread.  He  at  first 
thought  that  the  silk  was  effectual  because  it  was  thin  ; 
but  on  replacing  a  broken  silk  loop  by  a  still  thinner  wire, 
he  obtained  no  action.  Finally  he  came  to  the  conclusion 
that  his  loops  were  effectual,  not  because  they  were  thin, 
but  because  they  were  silk.  This  was  the  starting-point 
of  our  knowledge  of  insulation." 

Gray  died  in  the  midst  of  his  work ;  and  the  report  of 
his  last  experiments  was  dictated  by  him  from  his  death- 
bed, to  the  secretary  of  the  Royal  Society. 

In  1733  Dufay,  a  French  physicist,  while  experimenting 
with  an  electrically  excited  body,  found  that  a  piece  of 
gold-leaf  floating  in  the  air  was  repelled  if  the  excited 
substance  was  glass,  and  attracted  if  the  excited  sub- 
stance was  resin.  And  hence  he  recognized  two  kinds  of 
electricity,  which  were  for  a  long  time  known  respectively 
as  vitreous  and  resinous.  There  is  no  such  real  distinc- 
tion, because  by  changing  the  rubbing  material  the  elec- 
tricity of  resin  can  be  obtained  upon  glass,  and  vice  versa. 
But  what  we  now  know  as  plus  or  positive  electricity  is 
that  produced  by  rubbing  glass  with  silk  ;  and  negative 
or  minus  electricity,  that  due  to  the  rubbing  of  resin  with 
flannel. 

The  electrical  apparatus  of  1730  was,  as  may  readily  be 
imagined,  very  crude.  We  reproduce  from  Dr.  Grave- 
sande's  treatise  of  that  date,  the  accompanying  represen- 
tation of  an  electrical  machine  of  the  period.  It  consists 
simply  of  a  glass  globe  G,  supported  on  tubes  which  are 
revolved  by  a  belt  from  the  -  large  pulley  R,  which  is 
rotated  by  the  handle  M.  One  of  the  tubes  has  an 


12 


THE  AGE  OF  ELECTRICITY. 


open  end,  and  is  provided  with  a  stop-cock  E.     Through 
this  tube  the  air  can  be  exhausted  from  the  interior  of 


Fig.  1.— Electrical  Machine  of  1730. 

the  globe.     Over  the  globe  is  an  arch  of  brass  wire  from 
which   are   suspended   threads.     The  hand  is  used  as  a 


DISCOVERIES   OF  EARLY  EXPERIMENTERS.     13 

rubber,  and  the  machine  as  shown  is  intended  to  demon- 
strate the  following  experiment :  — 

"  Whirl  the  globe,  and  apply  the  hand,  and  immediately 
the  threads  will  be  moved  irregularly  by  the  agitation  of 
the  air ;  but  when  the  glass  is  heated  by  the  attrition,  all 
the  threads  are  directed  toward  the  centre  of  the  globe, 
as  may  be  seen  in  the  figure  ;  and,  if  the  hand  be  applied 
a  little  on  one  side,  or  nearer  the  pole  of  the  globe, 
the  threads  will  be  directed  toward  that  point  of  the  axis 
which  is  tinder  the  hand.  If  the  air  be  drawn  out  of  the 
globe,  this  whole  effect  ceases." 

This  machine  had  a  very  disagreeable  habit  of  explod- 
ing by  reason  of  the  expansion  of  the  air  within  the  glass 
globe,  caused  by  the  heating  of  the  latter  by  friction. 

We  have  already  stated  that  Otto  von  Guericke  made 
his  electrical  machine  from  a  globe  of  sulphur.  For  the 
sulphur  globe,  Hawksbee  and  Winkler  substituted  the 
glass  globe  represented  in  the  engraving.  The  prime 
conductor,  at  first  a  tin  tube  supported  by  resin  or  sus- 
pended by  silk,  and  nearly  equal  in  importance  to  the 
glass  insulator  which  is  to  be  excited,  was  not  invented 
until  ten  years  after  by  Boze  of  Wittenberg  (1741)  ;  and 
Winkler  of  Leipsic  suggested  a  fixed  cushion  instead  of 
the  human  hand  as  a  rubber.  Still  later  Gordon  of  Erfurt 
substituted  a  glass  cylinder  for  the  globe;  and  in  1760 
Planta  introduced  the  circular  plate  of  glass  still  used. 

In  the  year  1745  a  discovery  was  made,  which  in  point 
'of  importance  overshadowed  every  thing  that  had  been 
previously  accomplished.  And  it  seems  as  if  the  time 
had  come  for  some  great  advance.  The  electrical  machine 
had  reached  a  form  in  which,  with  little  variation,  it  has 
since  remained.  Large  pieces  of  electrical  material  had 
been  used  to  produce  manifestations  sufficiently  potent  to 
suggest  thunder  and  lightning ;  and  certain  properties  of 


14  THE  AGE  OF  ELECTRICITY. 

the  electric  fluid,  or  aura,  or  whatever  it  might  be,  had  been 
more  or  less  perfectly  recognized.  Yet,  after  all,  what 
practical  advantage  to  mankind  had  been  gained  ?  Curious 
things  had  been  developed,  as  wonderful  as  any  thing  the 
conjurers  could  do ;  but  beyond  gratifying  the  natural 
taste  for  the  marvellous,  and  furnishing  food  for  the 
speculations  and  material  for  the  lecture-room  experi- 
ments of  a  few  philosophers,  all  that  had  been  done  had 
added  nothing,  so  far  as  then  appeared,  to.  that  knowledge 
which  directly  contributes  to  human  welfare. 


THE  CAGING   OF  THE  LIGHTNING.  15 


CHAPTER  III. 

THE    CAGING    OF   THE    LIGHTNING. 

ON  Oct.  11,  1745,  Dean  von  Kleist  of  the  cathedral  of 
Camin,  in  Germany,  made  an  experiment  which  on  the 
following  4th  of  November  he  describes  in  a  letter  to  Dr. 
Lieberkuhn  of  Berlin,  in  the  following  terms  :  — 

"  When  a  nail  or  a  piece  of  brass  wire  is  put  into  a 
small  apothecaries'  phial  and  electrified,  remarkable  effects 
follow  ;  but  the  phial  must  be  very  dry  and  warm.  I  com- 
monly rub  it  over  beforehand  with  a  finger  on  which  I  put 
some  powdered  chalk.  If  a  little  mercury  or  a  few  drops 
of  spirits  of  wine  be  put  into  it,  the  experiment  succeeds 
the  better.  As  soon  as  this  phial  and  nail  are  removed 
from  the  electrifying  glass,  or  the  prime  conductor  to 
which  it  hath  been  exposed  is  taken  away,  it  throws  out 
a  pencil  of  flame  so  long  that  with  this  burning  machine 
in  my  hand  I  have  taken  about  sixty  steps  in  walking 
about  my  room  ;  when  it  is  electrified  strongly  I  can  take 
it  into  another  room,  and  then  fire  spirits  of  wine  with  it. 
If  while  it  is  electrifying  I  put  my  finger  or  a  piece  of  gold 
which  I  hold  in  my  hand  to  the  nail,  I  receive  a  shock 
which  stuns  my  arms  and  shoulders." 

This  was  the  first  announcement  of  the  possibility  of 
accumulating  electricity. 

In  the  following  year  Cunseus  of  Leyden  made  substan- 
tially the  same  discovery.  It  caused  great  wonder  and 


16  THE  AGE  OF  ELECTRICITY. 

dread,  which  arose  chiefly  from  the  excited  imagination. 
Musscheubroek  felt  the  shock,  and  declared  in  a  letter  to 
a  friend,  that  he  would  not  take  a  second  one  for  the  crown 
of  France.  Bleeding  at  the  nose,  ardent  fever,  a  heavi- 
ness of  head  which  endured  for  days,  were  all  ascribed  to 
the  shock.  Boze,  on  the  other  hand,  seems  to  have  coveted 
electrical  martyrdom  ;  for  he  is  said  to  have  expressed  a 
wish  to  die  by  the  electric  shock,  "  so  that  an  account  of 
his  death  might  furnish  an  article  for  the  Memoirs  of  the 
French  Academy  of  Sciences." 

Winkler,  his  coadjutor  in  the  improvement  of  the  elec- 
trical machine,  "  suffered  great  convulsions  through  his 
body,"  which  "  put  his  blood  into  agitation  ;  "  and  his  wife, 
who  took  the  shock  twice,  was  rendered  so  weak  by  it  that 
she  could  hardly  walk.  Nothing  daunted,  this  adventur- 
ous lady  (who  shall  say  whether  from  scientific  interest  or 
feminine  curiosity?)  persisted  in  being  shocked  for  the 
third  time  ;  and  then  her  previous  ailments  were  augmented 
by  the  nosebleed. 

After  the  philosophers  had  got  through  administering 
shocks  to  themselves  and  to  their  immediate  relatives,  and 
had  recovered  in  some  measure  their  mental  as  well  as  per- 
sonal equilibrium,  —  and  it  might  equally  well  be  added, 
their  moral  balance,  for  as  a  matter  of  fact  their  reports 
as  to  the  force  of  the  shock  and  its  attendant  disastrous 
effects  were  all  more  or  less  grossly  exaggerated,  —  they 
sot  about  seeing  what  this  extraordinary  discovery  really 
amounted  to.  What  Von  Kleist  actually  did  was  simply 
to  insert  a  nail  through  a  cork  into  a  phial  into  which  he 
poured  a  little  mercury,  spirits,  or  water.  Why  this  sim- 
ple contrivance  should  produce  the  observed  effects,  Von 
Kleist  did  not  know ;  but  Cunseus  and  the  other  Leyden 
philosophers  solved  the  problem,  and  in  this  way  Von 
Kleist's  apparatus  came  to  be  known  as  the  Leydeu-jar, 


THE   CAGING   OF  THE  LIGHTNING.  17 

Subsequently  the  jar  was  constructed  by  Dr.  Bevis  in  the 
form  shown  in  Fig.  2,  which  is  that  which  it  has  ever  since 
had.  In  charging  the  jar,  the  outer  coating,  usually  of  tin- 
foil, is  connected  with  the  earth  ; 
and  the  inner  coating  of  the  same 
material,  by  means  of  the  central 
wire  and  knob,  receives  the  sparks 
from  an  electric  machine.  The 
positive  electricity  from  a  glass 
electrical  machine,  passing  to  the 
inner  coating,  acts  inductively 
across  the  glass  upon  the  outer  Fig.  2. 

coating,  and  is  supposed  to  at- 
tract only  its  negative  electricity,  while  the  positive  elec- 
tricity there  resident  is  repelled  into  the  earth,  with  which 
the  outer  coating  is  connected.  In  this  way  two  opposite 
and  mutually  attracting  electricities  are  separated  by  the 
glass.  But  if  a  path  be  provided  by  which  these  two 
electricities  can  flow  to  one  another,  they  will  do  so,  and 
the  jar  will  be  discharged.  If  the  outer  coating  be  grasped 
with  one  hand,  and  the  knuckle  of  the  other  hand  be  pre- 
sented to  the  knob  of  the  jar,  the  body  will  then  form  a 
conducting  path  over  which  this  flow  can  take  place  ;  a 
bright  spark  will  pass  between  the  knob  and  the  knuckle, 
with  a  sharp  report ;  and  at  the  same  moment  a  convulsive 
"shock"  will  be  communicated  to  the  muscles  of  the 
wrists,  elbows,  and  shoulders. 

In  Von  Kleist's  apparatus,  the  water  or  mercury  formed 
the  inner  conducting  coating,  and  his  hand,  grasping  the 
bottle,  the  outer  coating  which  was  thus  connected  to  earth 
through  his  body.  When  he  touched  the  nail  with  his  dis- 
engaged hand,  he  completed  the  path  between  the  inner 
and  outer  coatings  through  his  body,  and  thus  received  the 
shock. 


18  THE  AGE   OF  ELECTEIC1TY. 

Scientists  everywhere  now  began  to  investigate  this 
phenomenon.  Graham  caused  a  number  of  persons  to  lay 
hold  of  the  same  metal  plate,  which  was  connected  with 
the  outer  coating  of  a  charged  Leyden-jar,  and  also  to 
grasp  a  rod  by  which  the  jar  was  discharged.  The  shock 
divided  itself  equally  among  them.  Abbe"  Nollet  procured 
a  detail  of  one  hundred  and  eighty  soldiers,  stood  them  up 
in  a  line,  and  sent  shocks  through  the  whole  battalion, — a 
significant  commentary  on  the  strength  of  military  disci- 
pline, which  could  make  ignorant  men  face  manifestations 
which  disconcerted  and  agitated  the  philosophers  them- 
selves. But  the  monks  outdid  the  soldiers  :  seven  hundred 
and  fifty  Carthusians  formed  a  line  5,400  feet  long,  an  iron 
wire  extending  between  each  two  persons  ;  when  the  abb6 
caused  the  discharge,  the  entire  company  of  ecclesiastics 
"gave  a  sudden  spring,  and  sustained  the  shock  at  the 
same  instant."  Apparatus  was  constructed  so  that  large 
quantities  of  electricity  could  be  accumulated,  and  results 
hitherto  unexpected  were  obtained.  Dr.  Watson  made 
experiments  to  discover  through  how  great  a  distance  the 
electric  shock  could  be  propagated,  and  in  1747  conveyed 
it  across  the  River  Thames  at  Westminster  Bridge,  and 
finally  concluded  that  "  the  velocity  of  the  electric  matter 
in  passing  through  a  wire  12,276  feet  in  length  is  instan- 
taneous." Other  investigators  killed  small  animals  and 
birds  with  powerful  discharges  from  the  Leyden-jar. 

In  1745  Mr.  Peter  Collinson  of  the  Royal  Society  sent 
a  jar  to  the  Library  Society  of  Philadelphia,  with  instruc- 
tions how  to  use  it.  This  fell  into  the  hands  of  Benjamin 
Franklin,  who  at  once  began  a  series  of  electrical  ex- 
periments. On  March  28,  1747,  Franklin  began  his 
famous  letters  to  Collinson,  regarding  which  Priestley 
says,  "  Nothing  was  ever  written  upon  the  subject  of 
electricity  which  was  more  generally  read  and  admired  in 


THE  CAGING   OF  THE  LIGHTNING.  19 

all  parts  of  Europe.  It  is  not  easy  to  say  whether  we 
are  most  pleased  with  the  simplicity  and  perspicuity  with 
which  they  are  written,  the  modesty  with  which  the  author 
proposes  every  hypothesis  of  his  own,  or  the  noble  frank- 
ness with  which  he  relates  his  mistakes  when  they  are 
corrected  by  subsequent  experiments."  In  these  letters 
he  propounded  the  single-fluid  theory  of  electricity,  and 
referred  all  electric  phenomena  to  its  accumulation  in 
bodies  in  quantities  more  than  their  natural  share,  or  to 
its  being  withdrawn  from  them  so  as  to  leave  them  minus 
their  proper  portion.  A  body  having  more  than  its  natural 
quantity,  he  regarded  as  electrified  positively,  or  plus;  and 
one  having  less,  as  electrified  negatively  or  minus.  On 
this  theory  he  explained  the  action  of  the  Leyden-jar  as 
it  has  already  been  explained  above  ;  and  he  conceived 
the  idea  of  connecting  together  a  number  of  Leyden-jars, 
the  outer  coating  of  each  being  connected  to  the  outer 
coating  of  the  next  succeeding  one,  and  thus  produced 
his  famous  "cascade  battery,"  in  which  the  strength 
of  the  shock  was  enormously  increased.  He  also  dis- 
covered that  the  connecting  coatings  of  the  Le}7den-jar 
"served  only,  like  the  armature  of  the  loadstone,  to  unite 
the  forces  of  the  several  parts,  and  bring  them  at  once  to 
any  point  desired  ; ' '  and  that  the  electricity  in  fact  existed 
only  upon  the  glass.  One  of  Franklin's  letters  to  Collin- 
son  is  celebrated  for  his  quaintly  humorous  proposition 
of  an  ; '  electric  feast "  to  be  held  on  the  banks  of  the 
Schuylkill.  Whether  this  ever  occurred,  is  questionable  ; 
but  Franklin's  description  of  it  is  well  worth  quoting. 
"  The  hot  weather  coming  on,"  he  says,  "  when  electrical 
experiments  are  not  so  agreeable,  it  is  proposed  to  put 
an  end  to  them  for  this  season,  somewhat  humorously, 
in  a  party  of  pleasure  on  the  banks  of  the  Schuylkill. 
Spirits,  at  the  same  time,  are  to  be  fired  by  a  spark  sent 


20  THE  AGE  OF  ELECTEICITY. 

from  side  to  side  through  the  river  without  any  other  con- 
ductor than  the  water  ;  an  experiment  which  we  some  time 
since  performed  to  the  amazement  of  many.  A  turkey 
is  to  be  killed  for  our  dinner  by  the  electric  shock,  and 
roasted  by  the  electric  jack  before  a  fire  kindled  by  the 
electric  bottle;  when  the  healths  of  all  the  famous  elec- 
tricians of  .England.  Holland,  France,  and  Germany  are 
to  be  drunk  in  electrified  bumpers,  under  a  discharge  of 
guns  from  the  electrical  battery."  If  Franklin's  proposal 
bordered  on  the  absurd  or  grotesque,  it  proves  how  near 
the  ridiculous  in  thought  may  be  to  the  sublime  ;  for  at 
that  same  period  he  was  formulating  the  speculations 
which  ultimately  culminated  in  one  of  the  most  audacious 
yet  most  brilliantly  successful  experiments  ever  made  by 
man.  More  than  forty  years  before,  Wall  had  compared 
the  crackling  from  his  rubbed  amber  to  thunder  and  light- 
ning ;  Nollet  in  France  had  not  long  before  quaintly 
said,  "  If  any  one  should  take  upon  him  to  prove  from  a 
well-connected  comparison  of  phenomena,  that  thunder  is 
in  the  hands  of  Nature  what  electricity  is  in  ours,  and 
that  the  wonders  which  we  now  exhibit  at  our  pleasure 
are  little  imitations  of  these  great  effects  which  frighten 
us  ;  I  avow  that  this  idea,  if  it  was  well  supported,  would 
give  me  a  great  deal  of  pleasure."  Meanwhile  the  facts 
derived  from  experiment  were  rapidly  multiplying,  which 
showed  the  similarity  between  the  powerful  sparks  of  the 
Leyden  battery  and  the  lightning  flash.  The  exag- 
gerated accounts  of  Musschenbroek  and  others  who  had 
received  the  shocks  went  to  prove  that  increase  in  force 
or  strength  would  cause  death.  Experiments  upon  birds 
and  small  animals  did  produce  death  as  sudden  as  that 
due  to  the  lightning  stroke.  Franklin  himself  was  twice 
struck  senseless  by  shocks  ;  and  he  afterwards  sent  the 
discharge  of  two  large  jars  through  six  robust  men,  who 


THE  CAGING   OF  THE  LIGHTNING.  21 

fell  to  the  ground,  and  got  up  again  without  knowing 
what  had  happened,  neither  feeling  nor  hearing  the  dis- 
charge. 

While  all  these  facts  convinced  Franklin  of  the  identity 
of  lightning  and  electricity,  they  demonstrated  at  the 
same  time  to  him  the  imminent  danger  which  must  attend 
any  experiment  which  would  serve  as  proof.  One  scarcely 
knows  which  to  admire  most,  the  lucid  reasoning  wherein 
he  states  his  convictions  to  Collinson,  or  the  cool  courage 
with  which  he  faced  not  only  possible  death,  but  the 
ridicule  of  the  world,  which  would  be  heaped  upon  his 
memory  in  event  of  failure.  The  result  would  brand  him 
as  a  madman  and  a  suicide,  or  raise  him  to  the  topmost 
pinnacle  of  human  fame.  The  account  given  by  Dr. 
Stuber  of  Philadelphia,  an  intimate  personal  friend  of 
Franklin,  and  published  in  one  of  the  earliest  editions  of 
the  works  of  the  great  philosopher,  is  as  follows :  — 

"The  plan  which  he  had  originally  proposed  was  to 
erect  on  some  high  tower,  or  other  elevated  place,  a  sen- 
try-box, from  which  should  rise  a  pointed  iron  rod,  insu- 
lated by  being  fixed  in  a  cake  of  resin.  Electrified  clouds 
passing  over  this  would,  he  conceived,  impart  to  it  a 
portion  of  their  electricity,  which  would  be  rendered  evi- 
dent to  the  senses  by  sparks  being  emitted  when  a  key, 
a  knuckle,  or  other  conductor  was  presented  to  it.  Phila- 
delphia at  this  time  offered  no  opportunity  of  trying  an 
experiment  of  this  kind.  Whilst  Franklin  was  waiting 
for  the  erection  of  a  spire,  it  occurred  to  him  that  he 
might  have  more  ready  access  to  the  region  of  clouds  by 
means  of  a  common  kite.  He  prepared  one  by  attaching 
two  cross-sticks  to  a  silk  handkerchief,  which  would  not 
suffer  so  much  from  the  rain  as  paper.  To  his  upright 
stick  was  fixed  an  iron  point.  The  string  was,  as  usual, 
of  hemp,  except  the  lower  end  which  was  silk.  Where 


22  THE  AGE   OF  ELECTEICITY. 

the  hempen  string  terminated,  a  key  was  fastened.  With 
this  apparatus,  on  the  appearance  of  a  thunder-gust  ap- 
proaching, he  went  into  the  common,  accompanied  by  his 
son,  to  whom  alone  he  communicated  his  intentions,  well 
knowing  the  ridicule  which,  too  generally  for  the  interest 
of  science,  awaits  unsuccessful  experiments  in  philosophy. 
He  placed  himself  under  a  shed  to  avoid  the  rain.  His 
kite  was  raised.  A  thunder-cloud  passed  over  it.  No 
signs  of  electricity  appeared.  He  almost  despaired  of 
success,  when  suddenly  he  observed  the  loose  fibres  of  his 
string  move  toward  an  erect  position.  He  now  pressed 
his  knuckle  to  the  key,  and  received  a  strong  spark.  How 
exquisite  must  his  sensations  have  been  at  this  moment ! 
On  his  experiment  depended  the  fate  of  his  theory. 
Doubt  and  despair  had  begun  to  prevail,  when  the  fact 
was  ascertained  in  so  clear  a  manner,  that  even  the  most 
incredulous  could  no  longer  withhold  their  assent.  Re- 
peated sparks  were  drawn  from  the  key,  a  phial  was 
charged,  a  shock  given,  and  all  the  experiments  made 
which  are  usually  performed  with  electricity."  And  thus 
the  identity  of  lightning  and  electricity  was  proved. 

Meanwhile,  Franklin,  in  his  letters  to  Collinson,  had 
already  outlined  his  proposed  experiments.  Collinson 
offered  the  letters  to  the  Royal  Society  for  publication, 
but  encountered  a  contemptuous  refusal.  The  suggestion 
that  pointed  rods  would  "probably  draw  the  electrical 
fire  silently  out  of  a  cloud  before  it  came  nigh  enough  to 
strike,  and  thereby  secure  us  from  that  most  sudden  and 
terrible  mischief,"  was  received  with  open  derision.  But 
some  years  later  the  Royal  Society  elected  Franklin  an 
honorary  member,  and  decreed  him  their  highest  honor, 
the  Copley  medal.  Franklin's  letters  were,  however,  pub- 
lished by  Dr.  Fothergitl.  They  went  through  five  editions 
in  London,  and  attracted  the  attention  of  all  Europe. 


THE   CAGING   OF  THE  LIGHTNING.  23 

An  incorrect  French  translation  falling  into  the  hands  of 
Buffon,  that  celebrated  philosopher  repeated  the  experi- 
ments successfully,  and  commended  them  to  his  friend  M. 
d'Alibard.  A  report  of  the  wonderful  results  reached 
Louis  XV.,  then  King  of  France;  and  at  his  request 
further  experiments  were  undertaken.  The  notice  of  the 
king  now  acted  as  a  stimulus  to  the  French  scientists  ;  and 
three  of  them,  Buffon,  De  Lor,  and  D'Alibard,  erected  ap- 
paratus for  attracting  the  lightning  at  different  localities. 
It  is  a  curious  fact,  that  despite  the  eagerness  of  these 
philosophers,  each  to  outstrip  the  other  in  being  the  first 
to  obtain  actual  results,  disappointment  awaited  them  all. 
D'Alibard  employed  an  old  soldier,  named  Coiffier,  to 
help  build  his  apparatus,  and  subsequently  to  watch  it.  It 
so  happened  that  the  long-expected  thunder-storm  came 
along  during  D'Alibard's  absence  ;  and  Coiffier,  who  had 
no  idea  of  the  danger  of  receiving  the  spark,  determined 
to  experiment  on  his  own  account.  Accordingly,  he 
mounted  the  insulated  stool  which  had  been  prepared, 
and  presented  a  wire  to  D'Alibard's  rod,  obtaining  a  fine 
spark,  —  and  then  another.  He  at  once  called  all  his 
neighbors,  and  some  one  ran  in  search  of  the  parish 
priest.  The  latter  was  seen  making  his  way  to  the  ap- 
paratus in  such  undignified  haste,  that  it  was  immediately 
surmised  that  the  daring  Coiffier  had  fallen  a  victim  to 
his  bold  experiment ;  and  accordingly  the  good  father 
found  himself  the  leader  of  a  miscellaneous  mob  of  vil- 
lagers. Regardless  of  the  pouring  rain  and  hail,  the 
crowd  surrounded  the  machine,  and  there  in  open-mouthed 
wonder  watched  the  priest  himself  draw  sparks  from  the 
rod.  Both  the  clergyman  and  the  soldier  managed  to  get 
lightly  struck, — so  lightly,  that,  in  their  absorbed  atten- 
tion to  the  sparks,  they  scarcely  noticed  the  occurrence 
until  afterwards,  when  each,  feeling  stinging  pains  in  his 


24  THE  AGE   OF  ELECTRICITY. 

fore-arm,  searched  for  the  cause,  and  found  bright  red 
stripes  on  the  flesh  just  as  if  a  few  sound  lashes  had 
been  administered.  It  is  very  likely  that  the  villagers 
saw  no  good  in  these  supernatural  manifestations  ;  and 
when  they  all  perceived  about  the  persons  of  the  priest 
and  his  companion  the  marked  odor  of  the  ozone  gener- 
ated, somewhat  sulphurous  in  character,  they  were  con- 
firmed in  their  idea  that  the  powers  of  the  nether  world 
had  been  invoked.  To  Coiffier,  however,  remained  the 
honor  of  being  the  first  to  receive  the  spark.  This  was 
on  May  10,  1752,  about  a  month  before  Franklin's  fa- 
mous experiment ;  and,  in  many  French  works,  priority  as 
the  original  discoverer  is  for  this  reason  patriotically 
claimed  for  D'Alibard.  There  is  no  doubt,  however,  that 
D'Alibard  obtained  his  instructions  from  Franklin's  let- 
ters, as  he  himself  afterwards  frankly  admitted  that  he 
merely  followed  the  tiack  which  Franklin  had  pointed 
out. 

The  European  philosophers  now  remitted  experiments 
to  find  out  how  strong  the  shock  of  the  Leyden-jar  was, 
and  turned  with  increased  enthusiasm  to  measuring  the 
power  of  the  lightning  stroke.  And  then  the  caged  light- 
ning found  its  first  victim.  In  the  engraving  of  the  old 
electrical  machine,  Fig.  1,  there  are  shown  a  number  of 
threads  which  hang  from  a  curved  support  over  the  glass 
globe,  and  which  are  attracted  by  the  globe  when  excited 
so  as  to  assume  an  inclined  position.  Professor  Richmann 
of  St.  Petersburg  had  constructed  an  "  electrical  gnomon  " 
on  this  same  principle  ;  his  idea  being,  to  measure  the 
strength  of  the  lightning  discharge  by  observing  the  angle 
of  inclination  assumed  by  a  suspended  thread  electrified 
thereby.  He  arranged  on  the  roof  of  his  house  an  iron 
rod  which  he  insulated  from  the  adjacent  part  of  the  build- 
ing ;  and  to  this  rod  he  fastened  a  chain  which  led  down 


THE   CAGING   OF  THE  LIGHTNING.  25 

into  his  laboratory,  and  was  connected  to  an  insulated 
support  from  which  hung  his  thread,  the  end  of  which 
extended  over  a  dial.  Richmaim  had  invited  an  engraver 
named  Solokow  to  witness  the  working  of  the  apparatus  ; 
and  as  a  thunder-storm  gathered,  the  two  men  eagerly 
watched  the  movement  of  the  thread.  Suddenly  a  peal  of 
thunder  of  terrific  loudness  was  heard.  Richmaim  bent 
forward  to  observe  his  thread  more  closely  ;  and  ' '  as  he 
stood  in  that  posture,  a  great  white  and  bluish  fire  ap- 
peared between  the  rod  of  the  electrometer  and  his  head. 
At  the  same  time  a  sort  of  steam  or  vapor  arose,  which 
entirely  benumbed  the  engraver,  and  made  him  sink  to  the 
ground."  The  apparatus  was  torn  to  pieces,  the  doors  of 
the  room  thrown  down,  and  the  house  violently  shaken. 
Richmaim's  wife,  running  into  the  room,  found  her  hus- 
band sitting  on  a  chest  which  happened  to  be  immediately 
behind  him.  He  was  stone  dead,  bearing  no  mark  beyond 
a  red  spot  on  his  forehead.  His  shoe  was  ripped  open 
and  his  waistcoat  singed,  showing  that  the  deadly  current 
had  passed  through  his  body.  Solokow  was  removed 
insensible,  but  subsequently  recovered.  The  luckless  ex- 
perimenter had  forgotten  to  provide  an  earth  connection 
whereby  the  charge  might  have  passed  harmlessly  to  the 
ground.  In  the  absence  of  this,  the  enormous  electro- 
motive force  of  the  current  was  sufficient  to  enable  it  to 
leap  over  the  interval  of  air  between  the  electrometer  and 
Richmann's  head,  and  so  to  be  led  through  his  body. 

Of  course  there  were  not  wanting  emotional  people  to 
draw  all  sorts  of  warnings  from  Richmann's  fate.  Frank- 
lin's proposition  to  erect  lightning-rods  which  would 
convey  the  lightning  to  the  ground,  and  so  protect  the 
buildings  to  which  they  were  attached,  found  abundant 
opponents,  who  agreed  with  Abbe  Nollet,  that  it  was  "  as 
impious  to  ward  off  Heaven's  lightnings  as  for  a  child  to 


26  THE  AGE  OF  ELECTRICITY. 

ward  off  the  chastening  rod  of  its  father."  Others,  whose 
religious  scruples  did  not  carry  them  quite  so  far,  went  to 
the  opposite  extreme,  and  concluded  that  if  there  was  any 
impiety^  about  lightning-rods,  it  lay  in  the  fact  that  they 
invited  the  u  chastening  rod/'  and  that  it  was  madness 
to  u  tempt  Providence  "  in  any  such  way.  Nevertheless, 
public  opinion  became  settled,  that  whether  lightning-rods 
were  impious  because  they  opposed  the  decree  of  Provi- 
dence, or  suicidal  because  they  induced  Providence  to 
make  decrees,  the  fact  remained  that  they  did  .protect 
buildings  ;  and  as  long  as  they  did  that,  the  theological 
questions  raised  might  be  left  to  time  for  settlement. 
Then  the  philosophers  raised  a  new  controversy  as  to 
whether  the  conductors  should  be  blunt  or  pointed  ;  Frank- 
lin, Cavendish,  and  Watson  advocating  points,  and  Wilson 
blunt  ends.  That  wise  monarch  whose  scientific  acumen 
stood  nonplussed  before  the  problem  of  how  apples  are 
got  into  dumplings,  graciously  considered  the  question,  be- 
cause it  affected  his  own  royal  abode,  Buckingham  Palace, 
and,  after  much  balancing  of  the  pros  and  cons,  reached 
the  sage  conclusion  that  the  pointed  conductors  ' '  were  a 
republican  device  calculated  to  injure  his  Majesty," 
whereupon  he  ordered  them  removed  from  the  palace,  and 
ball  conductors  substituted.  The  same  public  opinion 
which  ran  counter  to  him  when  he  tried  rather  fruitlessly 
to  repress,  some  years  later,  numerous  other  republican  de- 
vices calculated  to  injure  his  Majesty  on  the  opposite  side 
of  the  Atlantic,  asserted  itself  here.  "The  king's  chan- 
ging his  pointed  conductors  for  blunt  ones,"  said  Franklin, 
"  is  a  small  matter  to  me.  If  I  had  a  wish  about  them, 
it  would  be  that  he  would  reject  them  altogether  as  in- 
effectual. For  it  is  only  since  he  thought  himself  and 
his  family  safe  from  the  thunder  of  heaven,  that  he  has 
dared  to  use  his  own  thunder  in  destroying  his  innocent 


THE  CAGING   OF  THE  LIGHTNING.  27 

subjects."  The  logic  of  experiment,  however,  showed 
the  advantage  of  pointed  conductors  ;  and  people  persisted 
then  in  preferring  them,  as  they  have  clone  ever  since. 

We  have  now  traced,  though  very  briefly,  the  progress 
of  knowledge  of  electricity,  from  the  germ  of  the  science 
which  lay  hidden  for  thousands  of  years  in  amber,  like 
the  insects  so  often  found  in  that  substance,  —  and  yet 
unlike  them,  for  it  possessed  immortality,  — up  to  the  first 
practical  application  of  that  knowledge  to  human  use  and 
benefit.  The  lightning  had  been  caged.  The  mighty 
force,  which  since  the  creation  of  mankind  had  aroused 
but  feelings  of  awe  and  terror,  could  now  be  confined  and 
examined,  or  diverted  at  will  from  its  path  of  destruction. 
The  wise  men  of  the  eighteenth  century  had  captured  the 
electrical  Pegasus :  it  remained  for  the  wiser  men  of 
the  nineteenth  to  yoke  him  to  the  plough. 


28  THE  AGE  OF  ELECTRICITY. 


CHAPTER    IV. 

ELECTRICITY   IN   HARNESS. 

THE  death  of  Richmann,  and  the  potent  effects  of  even 
small  discharges  of  electricity  upon  the  human  body, 
caused,  as  may  be  well  imagined,  much  speculation  as  to 
the  part  which  an  electric  discharge  could  be  made  to 
take  in  curing  the  ills  that  flesh  is  heir  to.  The  electric 
machine  was  of  course  the  only  available  means  of  artifi- 
cially producing  the  current ;  and  the  modern  practitioner 
can  easily  figure  to  himself  the  unhappy  experiences  of 
patients  who  were  subjected  to  its  unregulated  and  power- 
ful discharges. 

Between  those  who  sought  to  use  electricity  as  a  nos- 
trum for  the  cure  of  all  ailments,  and  those  who  investi- 
gated its  action  physiologically,  there  was  a  wide  difference. 
Through  the  latter  class  of  investigators  many  discoveries 
of  great  value  were  made,  and,  finally,  one  of  the  utmost 
importance.  Beccaria  and  others  meanwhile  observed  the 
effects  of  the  electric  discharge  upon  the  muscles,  and  had 
noted  that  those  of  the  leg  of  a  cock  were  strongly  con- 
tracted when  a  shock  passed  through  them. 

In  1786  Luigi  Galvani,  medical  lecturer  at  the  Univer- 
sity of  Bologna,  while  engaged  upon  investigations  similar 
to  those  of  Beccaria,  prepared  some  frogs'  legs,  with  the 
object  of  observing  whether  any  effect  would  be  produced 
upon  them  by  the  electricity  of  the  atmosphere.  To  this 


ELECTRICITY  IN  HARNESS.  29 

end,  after  carefully  skinning  the  legs,  he  hung  them  upon 
a  hook  which  protruded  from  the  railing  of  his  balcony. 
lie  stood  watching  them  for  some  time,  but  no  results 
showed  themselves.  Finally,  disappointed,  he  lifted  them 
from  the  hook  ;  and  then,  while  in  the  act  of  so  doing, 
he  noticed  to  his  astonishment  that  the  very  effects,  the 
peculiar  muscular  contractions,  which  he  expected  the 
atmospheric  electricity  would  cause,  were  taking  place. 
As  it  was  evident  that  the  surrounding  atmosphere  had 
no  part  in  the  phenomenon,  he  at  once  sought  for  the 
concealed  cause  ;  and  finally  he  found  that  the  limbs  con- 
tracted whenever  the  iron  railing  touched  their  moist  sur- 
face, their  contact  meanwhile  with  the  hook,  which  was  of 
copper,  being  still  maintained.  Conjecturing  that  the  hook 
and  railing,  of  course,,  as  such,  had  nothing  to  do  with  the 
matter,  he  made  a  metallic  arc,  formed  of  two  pieces  of 
iron  and  copper ;  and  with  this  he  soon  found  that  it  was 
necessary  simply  to  bring  one  metal  into  contact  with  a 
nerve  or  with  the  end  of  the  spine,  and  the  other  into 
contact  with  a  muscle  of  the  leg,  to  produce  immediately 
muscular  contractions. 

Galvani  came  to  the  conclusion  that  the  electricity  of 
which  he  had  observed  the  effects  resided  in  the  muscles, 
which  received  their  supply  from  the  nerves  and  blood  ; 
and  in  1791  he  published  his  celebrated  work  on  the  sub- 
ject. If  people  believed  that  electricity  was  a  valuable 
remedy  before  this,  they  now  began  enthusiastically  to 
accept  the  shock  as  a  universal  panacea.  Du  Bois  Rey- 
mond  says,  that  wherever  frogs  were  to  be  found,  and 
where  two  different  kinds  of  metal  could  be  procured, 
everybody  was  anxious  to  see  the  mangled  limbs  of  frogs 
brought  to  life  in  this  wonderful  way.  The  physiologists 
believed  that  at  length  they -could  realize  their  visions  of 
a  vital  power.  The  physicians  whom  Galvani  had  some- 


30  THE  AGE   OF  ELECTRICITY. 

what  thoughtlessly  led  on  with  attempts  to  explain  all 
kinds  of  nervous  diseases,  as  sciatica,  tetanus,  and  epi- 
lepsy, began  to  believe  that  no  cure  was  impossible. 

It  is  a  curious  circumstance  in  matters  of  invention, 
that  discoveries  of  the  most  important  nature  have  been 
frequently  made  by  people,  who,  being  unable  to  realize 
their  importance,  have  passed  them  by,  leaving  them  to  be 
made  over  again  by  others.  The  electrical  effects  of  dis- 
similar metals  upon  animal  substance  had  been  observed 
by  Sulzer,  a  German  investigator,  some  twenty-three  years 
before  Galvani  made  his  experiments.  Sulzer  applied  the 
two  metals,  one  above  and  the  other  below  the  tongue, 
and  then  on  bringing  them  into  contact  perceived  the 
peculiar  sour  taste.  He  ascribed  this  sensation  to  some 
vibratory  motion,  excited  by  the  contact  of  the  metals, 
and  communicated  to  the  nerves  of  the  tongue ;  and  then, 
content  with  this  loose  and  fanciful  explanation,  he  an- 
nounced the  fact  in  17G7,  in  a  work  entitled  "The  General 
Theory  of  Pleasures,"  where  it  remained  wholly  unnoticed 
until  long  after  Galvani's  discovery  had  aroused  the  atten- 
tion of  the  world.  Galvani's  discovery  was  also  to  some 
extent  anticipated  by  Cotugno,  a  Neapolitan  professor  of 
anatomy,  who  in  1786  published  the  curious  statement 
that  one  of  his  pupils,  feeling  a  sharp  pain  in  the  lower 
part  of  his  leg,  clapped  his  hand  upon  the  spot,  and  'cap- 
tured a  mouse  which  had  bit  him.  The  little  animal,  after 
being  killed,  was  made  a  subject  for  dissection.  During 
this  proceeding  the  pupil  "  accidentally  touched  the  dia- 
phragmatic nerve  with  his  scalpel,  and  then  received  a 
shock  strong  enough  to  make  him  snatch  away  his  hand." 
Cotugno's  report  attracted  considerable  attention  through- 
out Italy,  and,  it  is  said,  caused  further  investigations  to 
be  made  by  Vassalli,  who  formulated  the  odd  theory  that 
nature  accumulates  electricity  in  certain  parts  of  animals, 


ELECTRICITY  IN  HARNESS.  31 

and  that  they  can  draw  upon  this  supply  at  will.  It  is 
quite  certain,  however,  that  the  work  of  both  Cotugno  and 
Sulzer  had  been  forgotten  when  Galvani's  discovery  was 
made ;  and  the  meagre  suggestions  published  by  them 
detract  nothing  from  the  honor  due  the  Bolognese  philoso- 
pher. But  Galvani  reaped  neither  profit  nor  glory  in  his 
lifetime.  The  Cisalpine  Republic  ordered  him  to  take  a 
certain  oath  entirely  contrary  to  his  political  and  religious 
convictions,  and,  on  his  refusal,  stripped  him  of  his  posi- 
tions and  titles.  Thus  reduced  to  poverty,  he  retired  to 
his  brother's  house,  and,  it  is  said,  fell  into  a  state  of 
lethargy,  whence  the  tardy  retraction  by  the  Government 
of  its  unjust  decree  failed  to  arouse  him,  and  in  which  he 
died.  Only  six  years  ago,  Bologna  erected  a  statue  to  his 
memory,  in  one  of  her  principal  squares,  and  so  made  that 
usual  reparation  of  the  public  to  unappreciated  genius. 

Some  two  years  after  Galvani's  results  and  theories  had 
been  published,  Alessandro  Volta,  a  professor  in  the  Uni- 
versity of  Pavia,  strongly  opposed  his  deductions. 

Volta  was  then  one  of  the  foremost  electricians  of  the 
day.     He  had  invented  the  electrophorus  and  the  electri- 
cal condenser  by  which  small  charges  of  electricity  were 
accumulated.     Volta  maintained  that  Galvani's  pretended 
animal  electricity  was  developed  simply  by 
the  contact  of   two  different    metals  ;   and 
thus  began  a  controversy  which  lasted  long 
after  Galvani's  death  in  1798.    Its  outcome 
was  the  invention  of  the  voltaic  pile,  which 
was  contrived  by  Volta  as  a  means  of  prov- 
ing his  theory.     He  soldered  together  two     Fig.  3.  —  Voita's 
disks,  one  of  copper  (c)  and  one  of  zinc  (z) . 
Between  these  he  placed  circular  pieces  of  woollen  cloth 
(/i),  moistened  with  a  solution  of  common  salt  or  diluted 
sulphuric  acid.     Several  sets  of  disks  thus  arranged  were 


32  THE  AGE   OF  ELECTRICITY. 

placed  one  above  the  other ;  each  pair  of  disks  in  the  pile 
was  separated  from  the  next  pair  by  a  moist  conductor. 
A  pile  composed  of  a  number  of  such  pairs  of  disks  will 
produce  electricity  enough  to  give  quite  a  perceptible 
shock,  if  the  top  and  bottom  disk,  or  wires  connected 
with  them,  be  touched  simultaneously  with  the  moist 
fingers. 

Volta's  next  step  was  the  invention  of  the  cup  form  of 
battery.  He  arranged  a  number  of  cups,  filled  either  with 
brine  or  dilute  acid,  into  which  dipped  a  number  of  com- 
pound strips,  half  zinc  and  half  copper ;  the  zinc  portion 
of  one  strip  dipping  into  one  cup,  while  the  copper  portion 
dipped  into  the  other.  In  each  cup,  therefore,  there  was 
a  copper  plate  and  a  zinc  plate,  separated  by  a  conducting 
fluid  ;  and  this  is  in  substance  the  voltaic  cell  of  to-day. 

In  discussing  the  sources  of  electricity,  we  shall  advert 
to  the  theory  and  operation  of  this  great  invention  which 
marks  the  beginning  of  a  new  era  in  the  progress  of  elec- 
trical science.  Even  as  Von  Kleist  and  Franklin  may  be 
said  to  have  caged  the  lightning,  so  Volta  tamed  it.  He 
made  electricity  manageable.  He  reduced  the  infinite  ra- 
pidity of  the  lightning  stroke  to  the  comparatively  slow 
but  enormously  powerful  current,  which  in  the  future  was 
destined  to  carry  men's  words  from  one  end  of  the  world 
to  the  other,  and  to  produce  the  dazzling  light  inferior 
only  to  the  solar  ray  ;  and  the  recognition  accorded  him 
might  well  have  satisfied  his  highest  ambition.  In  marked 
contrast  to  the  fate  of  the  broken-hearted  Galvani,  it  was 
Volta's  fortune  to  be  called  to  Paris  by  Napoleon,  then 
nearing  the  zenith  of  his  glory,  in  order  to  explain  his 
discoveries  before  the  assembled  philosophers  of  France. 
The  First  Consul  himself  presided ;  and  when  Volta's 
demonstration  was  completed,  it  was  Napoleon  who  pro- 
posed that  the  rules  of  the  Academy  should  be  suspended, 


ELECTRICITY  IN  HARNESS,  33 

and  that  the  gold  medal  of  the  Institute  immediately 
should  be  awarded  Volta  in  testimony  of  the  gratitude  of 
the  French  nation.  On  the  same  day  two  thousand  crowns 
were  sent  to  Volta  from  the  national  treasury ;  and,  as  a 
final  and  lasting  honor,  Napoleon  founded  the  award  of 
an  annual  medal  of  the  value  of  three  thousand  francs 
for  the  best  experiment  in  electricity,  and  a  prize  of  sixty 
thousand  francs  to  him  who  should  give  electricity  or 
magnetism,  by  his  researches,  an  impulse  comparable  to 
that  which  it  received  from  the  discoveries  of  Franklin 
and  Volta. 

And  yet,  singularly  enough,  we  speak  almost  instinc- 
tively of  the  galvanic,  seldom  of  the  voltaic,  cell,  —  as 
if  posterity  had  been  guided  by  sympathy  for  the  unfor- 
tunate, rather  than  by  a  sense  of  justice  to  the  favored, 
discoverer.  Such  words  as  "•  galvanize"  and  "galvanic," 
possessing  even  a  figurative  meaning,  are  in  every-day 
speech.  Volta's  name  is  embalmed  only  in  the  techni- 
calities of  the  science. 

Among  those  who  had  studied  deepest  into  the  phenom- 
ena of  galvanic  electricity  was  Hans  Christian  Oersted,  a 
Danish  physicist,  and  professor  of  physics  in  the  University 
of  Copenhagen.  Oersted's  researches  led  him  to  suspect 
the  identity  of  magnetism  and  electricity,  but  for  a  long- 
time no  means  of  experimentally  proving  the  fact  revealed 
itself.  The  expedient  had  been  tried  of  placing  the  two 
poles  of  a  battery,  as  highly  charged  as  possible,  in  a 
parallel  line  with  the  poles  of  a  magnetic  needle,  without 
results.  In  one  of  the  reports  of  the  Smithsonian  Insti- 
tute, the  story  of  his  discovery  is  thus  graphically  told  : 
"Fortune,  it  might  be  said,  ceased  to  be  blind  at  the 
moment  when  to  Oersted  was  allotted  the  privilege  of  first 
divining  that  it  was  not  electricity  in  repose  accumulated 
at  the  two  poles  of  a  charged  battery,  but  electricity  in 


34  THE  AGE  OF  ELECTRICITY. 

movement  along  the  conductor  by  which  one  of  the  poles 
is  discharged  into  the  other,  which  would  exert  an  action 
on  the  magnetic  needle.  While  thinking  of  this  (it  was 
during  the  animation  of  a  lecture  before  the  assembled 
pupils),  Oersted  announces  to  them  what  he  is  about  to 
try  :  he  takes  a  magnetic  needle,  places  it  near  the  electric 
battery,  waits  till  the  needle  has  arrived  at  a  state  of  rest ; 
then  seizing  the  conjunctive  wire  traversed  by  the  current 
of  the  battery,  he  places  it  above  the  magnetic  needle, 
carefully  avoiding  any  manner  of  collision.  The  needle  — 
everyone  plainly  sees  it — the  needle  is  at  once  in  motion. 
The  question  is  resolved.  Oersted  has  crowned,  by  a 
great  discovery,  the  labors  of  his  whole  precious  life." 

On  July  21,  1820,  the  discovery  was  announced,  that  a 
galvanic  current  passing  through  a  wire  placed  horizontally 
above  and  parallel  to  an  ordinary  compass-needle,  will 
cause  that  needle  to  sway  on  its  axis  to  the  east  or  west, 
according  to  the  direction  of  the  current  through  the  wire. 
Oersted's  discovery  may  be  said  to  have  pointed  the  way 
to  the  great  applications  of  electricity  to  human  use  ;  for 
it  showed  that  energy  in  the  form  of  electricity  could  be 
converted  into  energy  in  the  form  of  mechanical  motion. 

The  discovery  of  the  electro-magnet  lay  but  a  step  be- 
yond,—  a  short  step,  —  and  it  was  quickly  taken.  And 
then  opened  the  era  of  electricity  at  work,  —  the  era  when 
the  discoverer  too  frequently  finds  his  sole  reward  in  the 
applause  of  his  compeers,  and  when  the  world  lavishes  its 
honors  and  wealth  upon  the  fortunate  inventor.  This  is 
the  era  in  which  we  live. 


THE  GALVANIC  BATTERY.  35 


CHAPTER  V. 

THE  GALVANIC  BATTERY,  AND  THE  CONVERSION  OP 
CHEMICAL  ENERGY  INTO  ELECTRICAL  ENERGY. 

WHAT  is  electricity?  No  one  knows.  It  seems  to  be 
one  manifestation  of  the  energy  which  fills  the  universe, 
and  which  appears  in  a  variety  of  other  forms,  such  as 
heat,  light,  magnetism,  chemical  affinity,  mechanical 
motion,  etc.  For  the  purposes  of  convenient  thinking,  it 
is  well  to  consider  the  electrical  current  as  a  fluid,  because 
it  apparently  follows  certain  laws  of  fluids. 

In  its  usual  form,  the  galvanic  cell  consists  of  any  two 
dissimilar  conducting  substances  subjected  to  the  action 
of  a  third  substance  capable  of  chemically  attacking  but 
one  of  them,  or  of  attacking  one. in  less  degree  than  the 
other.  There  is  a  containing  vessel,  in  which  is  placed  a 
liquid  called  the  electrolyte  ;  and  in  this  liquid  are  plunged 
the  two  conducting  substances,  usually  in  solid  form,  which 
are  called  the  elements,  one  of  which  is  attackable  by  the 
liquid,  and  the  other  non-attackable  or  less  attackable. 
When  the  two  conducting  bodies  are  connected  by  a  wire 
of  conducting  material,  then  an  electrical  current  will  cir- 
culate, and  will  proceed  from  the  body  that  is  attacked 
to  the  body  that  is  not  attacked,  by  way  of  the  liquid, 
and  thence  back  to  the  attacked  body  by  the  wire.  The 
path  thus  traversed  by  the  Current  is  its  circuit.  If  the 
circuit  is  anywhere  interrupted,  the  current  stops. 


36 


THE  AGE   OF  ELECTRICITY. 


Fig.  4. 


The  diagram  (Fig.  4)  will  make  this  quite  clear.  Here 
the  wires  are  attached  to  the  two  bodies,  immersed  in  a 
liquid  which  will  chemically  attack  one  of  them.  The 
current  then  circulates  in  the  direction 
of  the  arrow,  from  A  the  attacked  body 
to  B  the  non-attacked  body,  and  thence 
back  through  the  connecting  wire. 

Almost  every  branch  of  science  now- 
adays has  its  own  language,  made  up 
of  its  technical  terms,  which  in  time 
become  absorbed  into  general  speech. 
This  is  fast  becoming  the  case  with  the 
language  of  electricity.  Amperes  and 
volts  and  ohms  are  no  longer  possessed 
of  meaning  only  to  the  initiated,  but  are  taking  their  place 
among  such  every-day  standards  as  pounds  and  gallons 
and  inches.  Although  this  little  work  makes  no  pretence 
to  be  a  treatise,  it  is  believed  that  a  plain  statement  of 
some  significations  will  be  of  service  to  the  reader  as  a 
help  to  a  clearer  comprehension  of  the  applications  of 
electricity  hereafter  described. 

If  we  run  or  walk,  or  saw  wood  or  pump  water,  we  are 
conscious  after  a  time  of  having  exerted  ourselves.  We 
have  apparently  expended  certain  of  our  bodily  energy 
in  accomplishing  something  against  an  opposing  force. 
That  is  to  say,  we  have  done  work.  Before  beginning 
the  task,  we  were  conscious  of  an  ability  to  undertake  it. 
At  the  end  of  the  task,  comes  a  sense  of  fatigue  which 
may  be  sufficiently  strong  to  demonstrate  our  inability  to 
repeat  the  same  labor  until  a  period  of  rest  and  recupera- 
tion intervenes.  At  the  outset,  therefore,  we  possess  a 
power,  ability,  or  potential,  to  exert  so  much  energy. 
After  the  exertion,  we  have  not  this  power,  because  we 
have  expended  the  energy  in  the  form  of  bodily  motions, 


THE  GALVANIC  BATTERY.  37 

against  the  opposing  forces  of  friction  or  gravity.  As 
we  have  already  stated,  electricity  is  simply  one  form  of 
energy,  and  when  it  is  exerted  against  opposition  it  does 
work.  But,  like  ourselves,  in  order  to  do  work,  it  must 
acquire  a  certain  condition. 

If  an  athlete  is  about  to  enter  into  an  exhausting  con- 
test, he  trains  himself  to  that  end  ;  and  by  dint  of  exercise, 
judicious  fare,  etc.,  he  brings  his  muscles  and  other 
organs  into  a  condition  competent  to  the  great  exertion 
before  him.  His  potential,  his  capacity  to  do  the  work,  is 
thus  enhanced.  And  so  in  general,  any  sort  of  education, 
whether  mental  or  physical,  simply  has  for  its  object  the 
raising  of  the  potential  of  the  brain  or  the  muscles,  to 
accomplish  certain  ends.  We  have  constantly  before  us 
examples  of  natural  forces  under  varying  potential.  A 
hot  iron  must  acquire  a  high  temperature  before  it  will  burn 
inflammable  bodies,  a  still  higher  one  that  it  may  be  welded, 
and  still  higher  that  it  may  melt.  Water  must  be  carried 
to  a  high  elevation  before,  by  its  fall,  it  can  turn  a  wheel. 
The  steam  in  a  boiler  must  reach  a  certain  pressure  before 
it  can  move  the  engine  piston.  And  so  also  electricity, 
before  it  can  do  work,  must  reach  a  certain  condition, 
analogous  in  some  degree  to  temperature  and  pressure. 

Suppose  we  had  a  tank  of  water  at  A  (Fig.  5),  elevated 
above  the  ground.  If  we  connect  a  pipe  B  to  ife,  the 
water  will  run  down.  What  determines  the  flow?  Simply 
the  elevation  of  the  water.  Again,  take  two  tanks,  one 
not  as  high  as  the  other,  but  both  higher  than  the  ground. 
The  water  of  course  flows  from  the  highest  one  J.,  to  the 
lower  one  B,  and  so  to  the  earth.  The  water  flows  from 
A  to  B  simply  because  of  their  difference  in  height ; 
and  this  difference  determines  the  flow  of  water  from 
one  tank  to  the  other,  or  from  either  tank  to  the 
ground.  Therefore  we  say  of  water,  that  its  ability  to 


38 


THE  AGE  OF  ELECTRICITY. 


do  work  by  exerting  pressure  (its  potential)  depends  on 
its  elevation. 

So  of  electricity.  A  body  may  be  electrified  up  to  a  cer- 
tain potential.  For  convenience  the  earth  is  considered  as 
of  zero  or  no  potential.  •  Then,  if  by  any  material  capable 
of  conducting  electricity  we  connect  the  electrified  body  to 
the  earth,  the  conditions  will  be  the  same  as  in  the  case  of 


Fig.  5. 


the  tank  of  water  (Fig.  5)  :  the  electricity  will  flow  from 
the  electrified  body  to  the  earth.  Again,  if  a  body  electri- 
fied to  a  high  potential  communicate  with  one  electrified 
to  a  low  potential,  then  the  electricity  (as  in  the  case  of 
the  water  between  the  tanks  A  and  B  in  Fig.  5)  will  flow 
from  the  body  at  high  potential  to  the  body  at  low  potential. 
There  is  a  force  which  moves  the  electricity  from  one 


THE  GALVANIC  BATTERY.  39 

point  to  another,  analogous  to  the  force  of  gravity  which 
makes  water  run  down  hill.  That  force  is  commonly 
called  electro-motive  force,  or,  as  it  is  sometimes  termed, 
electrical  pressure. 

We  have  said  that  work  is  energy  exerted  against  an 
opposing  force,  or,  in  other  words,  against  a  resistance. 
This  resistance,  in  the  case  of  water,  may  be  due  to  fric- 
tion against  the  sides  of  a  pipe,  or  to  the  opposition  to 
the  flow  offered  by  an  interposed  water-wheel  which  drives 
machinery.  Electricity  in  motion  in  the  same  way  does 
work,  and  that  which  opposes  its  motion  is  technically 
called  the  resistance. 

Certain  bodies,  as  glass  and  India  rubber,  offer  very 
great  resistance  to  the  electric  flow  :  these  are  known  as 
insulators.  Others  offer  very  little  resistance,  and  these 
are  termed  conductors. 

In  order  to  maintain  a  constant  flow  or  current  of  elec- 
tricity, there  must,  as  we  have  seen,  be  a  difference  of 
potential  between  two  points  between  which  a  conductor 
extends  ;  and  this  difference  of  potential  must  be  kept  up, 
otherwise  the  current  would  simply  equalize  itself  at  both 
points,  just  as  water  will  rise  to  its  own  level  and  then 
cease  flowing.  The  current  is  urged  along  the  conductor 
by  its  electro-motive  force,  and  it  is  opposed  by  whatever 
resistance  lies  in  its  path.  The  greater  the  electro-motive 
force  in  proportion  to  the  resistance,  the  greater  will  be 
the  strength  of  the  current ;  or,  to  use  the  water  analogy 
again,  the  more  gallons  of  water  (for  example)  will  flow 
through  the  pipe  in  a  given  time.  Conversely,  the  greater 
the  resistance,  the  more  opposition  the  current  will  meet, 
and  hence  the  weaker  it  will  be. 

This  simple  relation  of  electro-motive  force  and  resist- 
ance is  the  fundamental  law  of  electricity  in  motion,  discov- 
ered by  Professor  Ohm,  a  distinguished  German  physicist. 


40  THE  AGE  OF  ELECTRICITY. 

Consequently  there  ar,e  three  things  about  any  electrical 
current  to  be  known  :  namely,  its  electro-motive  force,  or 
pressure ;  the  resistance  which  it  encounters ;  and  the 
strength  of  the  current,  which  depends  upon  these. 

We  measure  steam  or  water  pressure  in  pounds  per 
square  inch,  heat  by  thermometric  degrees,  distances  by 
feet  and  inches,  and  so  on.  Electro-motive  force  is  meas- 
ured in  volts.  A  volt  is  very  nearly  the  pressure  yielded 
by  a  certain  standard  galvanic  cell,  usually  the  Daniell 
hereafter  described.  The  term  has  also  a  very  accurate 
mathematical  signification,  which  need  not  be  discussed 
here. 

Resistance  is  measured  in  ohms.  A  column  of  mercury 
one  millimetre  in  cross  section,  and  106.2  centimetres  in 
length,  has  a  resistance  of  one  ohm  ;  but,  for  convenience, 
it  may  be  remembered  that  ordinary  iron  telegraph-wire 
has  a  resistance  of  about  13  ohms  to  a  mile. 

An  electrical  current  having  an  electro-motive  force  of 
one  volt,  traversing  a  resistance  of  one  ohm,  is  said  to 
have  a  strength  of  one  ampere. 

Here  we  diverge  a  little  from  the  water  analogy.  If 
we  referred  to  water,  we  should  say  that  water  under  so 
many  pounds  pressure  per  inch,  going  through  a  pipe  of 
a  certain  diameter,  is  delivered  at  the  rate  of  so  many 
gallons  (for  example)  per  minute.  If  we  had  some  one 
word  which  meant  "gallons  per  minute,"  that  would  cor- 
respond to  ampere.  When  a  current  of  one  ampere 
strength  flows  for  one  second,  the  quantity  of  electricity 
delivered  is  called  one  coulomb.  A  current  of  the  strength 
of  one-tenth  ampere  will  not  yield  a  quantity  of  electricity 
equal  to  a  coulomb  until  it  has  flowed  ten  seconds. 

To  recapitulate  in  briefer  terms  :  Electro-motive  force 
means  electrical  pressure.  Resistance  has  its  obvious 
meaning.  Electro-motive  force  is  not  measured  in  pounds 


THE   GALVANIC  BATTERY.  41 

per  square  inch  like  steam  or  water  pressure,  but  in  volts ; 
and  a  volt  is  the  pressure  given  by  one  standard  cell. 

Resistance  is  measured  in  ohms,  and  an  ohm  answers  to 
the  resistance  offered  by  four  hundred  and  sixty  feet  of 
ordinary  telegraph-wire,  approximately.  Strength  of  cur- 
rent is  measured  in  amperes.  Speaking  of  a  water-wheel, 
we  say  we  need  a  current  flowing  at  the  rate  of  so  many 
gallons  per  minute  to  drive  it.  Speaking  of  an  electric 
lamp,  we  say  we  need  a  current  of  from  one  to  fifty  am- 
peres to  keep  it  glowing.  The  term  "coulomb"  is  far 
less  employed  in  practice  ;  but  it  may  be  in  the  end  most 
familiar  of  all,  for  when  the  electric  light  comes  into  use 
in  dwellings,  we  shall  pay  for  our  electrical  supply  at  so 
much  per  thousand  coulombs,  for  example,  as  we  now  pay 
for  gas  at  so  much  per  thousand  cubic  feet. 

To  return  now  to  the  galvanic  battery :  It  is  not  neces- 
sary here  to  review  the  various  theories  suggested  to 
account  for  its  behavior.  These  are  all  in  the  regular 
treatises  ;  and  whether  the  current  be  due  to  contact  of 
dissimilar  substances,  or  to  chemical  action  in  the  cell, 
was  a  subject  warmly  discussed  by  the  grandfathers  of  the 
present  generation.  It  is  better  for  present  purposes  to 
take  the  facts  as  we  find  them,  and  look  upon  the  cell  in 
the  light  of  what  we  see  happening  in  it ;  and,  of  these 
happenings,  the  principal  ones  necessarily  attend  the  de- 
velopment of  the  current,  and  essential  thereto  is  the 
chemical  action  on  one  of  the  bodies,  or  so-called  ele- 
ments, therein.  In  fact,  any  chemical  re-action  which 
occurs  between  conducting  substances  may  be  utilized  to 
generate  electric  currents.  The  chemical  affinity  both  sup- 
plies and  measures  exactly  the  electro-motive  force. 

There  are  some  very  curious  but  important  facts  now  to 
be  noted  about  galvanic  cells  and  their  currents.  The  size 
of  the  cell  has  nothing  to  do  with  the  electrical  pressure 


42  THE  AGE  OF  ELECTRICITY. 

yielded, — the  electro-motive  force.  A  cell  the  size  of 
a  percussion-cap  will  give  just  as  high  an  electro-motive 
force  as  a  cell  as  big  as  the  distributing  reservoir  in  New- 
York  City.  Electro-motive  force,  as  we  have  stated,  de- 
pends on  difference  of  potential ;  difference  of  potential 
exists  in  all  dissimilar  electrified  bodies.  Whether  they 
are  large  bodies  or  small  ones,  is  beside  the  question  ;  just 
as  the  fact  that  the  pressure  of  water,  due  to  its  flow  from 
a  reservoir  to  a  plain  beneath,  is  not  influenced  at  all  by 
the  area  of  the  reservoir,  but  by  the  height  of  the  water- 
level  above  the  plain.  Water-pressure  is  the  same  per 
foot  of  vertical  height,  no  matter  whether  the  column  is  at 
its  base  a  square  inch  or  a  square  mile  in  area.  The  two 
connecting  bodies  in  the  cell,  when  one  is  attackable  and 
attacked  by  the  liquid,  are  at  different  potential :  that  of 
the  attacked  body  is  the  highest.  The  current  then  flows 
to  the  non-attacked  body  through  the  conducting  liquid, 
and  then  back  by  the  wire  to  the  attacked  body.  The 
constant  chemical  attack  keeps  the  current  flowing.  A 
current  of  water  will  flow  from  a  high  place  to  a  low  place 
by  gravity,  but  it  will  not  flow  up  hill  again  unless  work 
is  done  to  force  it  up.  So,  in  a  cell,  the  current  will  flow 
from  high  potential  to  low  potential,  but  not  back  again. 
Work  is  required  to  send  it  back,  and  this  the  chemical 
action  supplies. 

When  we  warm  our  houses,  or  drive  a  steam-engine,  we 
know  that  the  amount  of  heat  v;e  get  in  the  first  case,  or 
power  in  the  second,  depends  upon  how  much  coal  we 
burn,  other  things  being  equal.  The  burning  of  coal  is 
simply  the  chemical  action  between  the  carbon  of  the  fuel 
and  tne  oxygen  of  the  air.  So,  in  a  galvanic  cell,  we  burn 
the  attacked  element.  As  we  convert  coal  into  ashes  of 
no  further  use  in  the  furnace,  to  produce  heat,  we  convert 
the  zinc  of  the  cell  into  another  substance  of  no  further 


THE   GALVANIC  BATTERY.  43 

use  in  the  cell  to  produce  electricity.  Through  the  steam 
boiler  and  engine  we  can  convert  chemical  action  into 
mechanical  work,  which  we  can  apply  to  drive  locomotives 
or  steamships  or  machinery. 

The  galvanic  cell  converts  chemical  action  into  elec- 
tricity. The  amount  of  work  realized  in  one  case,  and 
of  electricity  in  the  other,  depends  on  the  amount  of  fuel, 
whether  coal  or  zinc,  consumed.  If,  then,  in  the  galvanic 
cell  we  burn  twice  as  much  zinc  in  a  given  time,  we 
shall  have  a  current  twice  as  strong.  We  can  do  this 
by  making  the  attacked  body  in  the  cell  larger,  so  as  to 
expose  double  the  area  to  the  attack. 

Hence  it  appears,  that,  while  the  size  of  the  bodies  in 
the  cell  has  no  bearing  on  the  pressure  of  the  current, 
it  has  a  very  material  bearing  on  the  strength  of  it.  It 
is,  as  we  have  said,  so  far  as  the  pressure  is  concerned, 
immaterial  whether  two  water  columns  of  the  same  height 
press  on  bases  of  a  square  inch  or  a  square  mile  in 
area ;  but  the  strength  of  the  two  currents,  the  gallons 
flowing  down  per  minute,  will  be  enormously  different. 
Consequently,  when  we  want  high-pressure  electricity, 
we  put  into  the  cell  bodies  which  are,  or  will  be,  of  widely 
different  potential ;  we  look  to  the  nature  of  the  bodies. 
When  we  want  great  strength  of  current,  we  look  to  their 
dimensions. 

In  practice,  however,  we  do  not  make  huge  cells,  chiefly 
because  of  their  cumbrousness  and  difficulty  to  handle. 
We  can  increase  either  the  electro-motive  force,  or  the 
strength  of  the  current,  by  using  several  cells  of  con- 
venient size,  and  connecting  them  together  differently. 
Thus,  in  Fig.  6,  each  cell  is  supposed  to  give  an  electro- 
motive force  of  one  volt.  If  we  connect  the  wire  of  the 
attacked  element  in  one  cell  to  the  unattacked  element  in 
the  next,  and  so  on,  we  shall  add  together  the  several 


44 


THE  AGE  OF  ELECTRICITY. 


electro-motive  forces  of   each,  and  obtain  an  aggregate 
pressure  of  four  volts,  while  the  strength  of  the  current 


Fig.  6. 


will  remain  the  same  as  that  of  one  cell.    If,  however,  we 
connect  all  the  attacked  elements  together  by  one  wire, 


Fig.  7. 

and  all  the  non-attacked  elements  together  by  another,  as 
in  Fig.  7,  then  we  shall  really  have  quadrupled  the  size 
of  the  elements ;  and  we  shall  have  a 
current  four  times  as  strong,  while  its 
pressure  will  remain  at  one  volt. 

Take  the  water  analogy  again.  Sup- 
pose we  start  with  a  tank  of  water  at  the 
level  marked  1  in  Fig.  8.  Then  the  water 
will  flow  out  with  a  certain  pressure,  de- 
pending on  the  elevation  of  the  tank.  So 
in  a  given  cell  the  current  will  flow  out 
with  a  given  electro-motive  force,  depend- 
ent on  the  materials  of  the  cell.  Let  us 
now  elevate  the  tank  to  position  2,  then 
we  have  doubled  the  water  pressure  ;  if 


Fig.  8. 


we  carry  it  to  the  position  3,  still  higher,  we  may  make 
the  pressure  three  times,  and  if  to  position  4,  four  times, 


THE   GALVANIC  BATTERY. 


45 


as  great.  We  do  the  same  thing  electrically  by  adding 
cells  as  shown  in  Fig.  6.  The  quantity  of  water  or  of 
electricity  yielded  remains  the  same,  but  its  pressure  in- 
creases. Suppose,  however,  that  we  start  again  with 
our  tank  of  water,  which,  however,  contains  say  but  ten 
gallons,  which  it  will  discharge  completely  in  a  minute. 
If  we  place  beside  it  three  other  tanks  of  equal  capacity, 
and  at  the  same  elevation,  each  one  will  discharge  ten 
gallons  a  minute,  or  all  together  forty  gallons  a  minute. 
This  is  the  parallel  case  to  that  of  connecting  the  cells 
as  in  Fig.  9.  The  pressure  of  water  or  electricity  re- 


Fig.  9. 

mains  the  same  ;  but  more  water  or  electricity  is  dis- 
charged in  a  given  time. 

Or,  to  put  this  in  a  more  practical  form,  suppose  we 
have  a  pipe  plenty  large  enough  to  carry  all  the  water  we 
need,  in  a  given  time,  to  the  top  of  a  house,  but  find 
the  water  will  not  come  up.  We  increase  the  water  press- 
ure, and  the  water  rises  to  the  desired  height.  That  is 
the  first  case.  Suppose,  again,  that  we  have  a  water- 
wheel  to  turn,  but  only  a  little  stream  delivered,  say,  from 
a  small  pipe,  with  great  force.  We  increase  the  size  of 
the  pipe,  and  get  more  water.  That  is  the  second  case. 
This  makes  the  foregoing  facts  easy  to  remember. 

When  the  current  in  a  cell  travels  from  the  attacked 
element  to  the  non-attacked  element,  through  the  liquid  in 
the  cell,  it  meets  with  resistance  ;  and  so,  also,  when  the 
current  travels  around  from  the  non-attacked  element  to 


46* 


THE  AGE  OF  ELECTRICITY. 


Fig.  10. 


the  attacked  element,  by  the  wire  outside  the  cell,  it  meets 
with  still  further  resistance. 

Here,  then,  are  two  places  where  the  current  will  meet 
obstacles  ;  one  inside  the  cell,  and  the 
other  outside  of  it.  The  resistance  offered 
by  the  liquid  inside  the  cell  is  called  the 
internal  resistance  ;  and  that  of  the  cir- 
cuit outside  the  cell,  the  external  resist- 
ance, —  as  illustrated  in  Fig.  10. 

The  external  resistance  we  control. 
It  may  be  due  to  many  miles  of  tele- 
graph-wire, or  to  the  coils  of  an  electric 
motor,  or  the  filament  of  an  electric  lamp, 
or  to  any  other  path  which  we  provide  for 
the  current,  in  traversing  which  it  does  the  work  we  desire. 
The  internal  resistance,  however,  is  peculiar  to  the  cell 
itself ;  and  whatever  work  the  current  has  to  do  to  get 
through  this  may  be  taken  as  wasted  energy.  Conse- 
quently it  is  necessary  to  make  the  internal  resistance  of 
the  cell  as  small  as  possible ;  and  to  do  this  there  are 
several  ways. 

It  requires  much  less  work  to  swim  ten  feet  than  twenty  : 
so  in  like  manner,  if  we  shorten  the  path  of  the  current 
through  the  liquid,  it  will  have  less  liquid  to  go  through, 
and  hence  meet  less  resistance.  Therefore  we  bring  the 
two  solid  bodies,  or  elements,  in  the  cell,  as  near  together 
as  possible  without  touching. 

If,  however,  for  any  reason  we  find  it  impracticable  or 
undesirable  thus  to  bring  the  plates  close  together,  we  can 
leave  the  thickness  of  the  intervening  liquid  as  it  is,  but 
increase  the  size  (surface  area)  of  the  plates.  Then  more 
of  the  attackable  body  will  be  attacked  in  a  given  time ; 
and,  as  we  have  already  seen,  we  shall  have  a  stronger 
current,  which  will  more  easily  overcome  the  resistance. 


THE  GALVANIC  BATTERY.  47 

In  the  first  case,  therefore,  we  actually  diminish  the 
resistance  by  diminishing  the  thickness  of  the  liquid,  the 
strength  of  the  current  remaining  the  same.  In  the  second 

&  O 

case,  we  neither  increase  nor  diminish  the  resistance  ;  but 
we  augment  the  current  strength,  so  that  the  obstacle  is 
more  easily  overcome. 

It  is  very  like  journeying  by  railway  from  one  place  to 
another.  We  can  take  a  slow  train  by  a  short  road,  or  a 
fast  train  over  a  long  road. 

There  is  one  more  very  important  fact  about  the  gal- 
vanic cell,  which  is  yet  to  be  noticed.  If  we  make  a 
simple  cell,  say  of  a  plate  of  copper  (the  unattacked  ele- 
ment) ,  a  plate  of  zinc  (the  attacked  element) ,  and  water, 
we  shall  find,  that  after  a  very  short  time  the  electro- 
motive force  of  the  cell  runs  down,  and  that  the  current 
very  perceptibly  weakens,  or  stops  altogether.  When  this 
happens,  if  we  examine  the  copper  plate  carefully  we  shall 
find  it  covered  with  minute  bubbles  of  gas.  This  gas  is 
hydrogen,  which  in  all  cells,  although  generated  at  the 
surface  of  contact  of  the  attacking  liquid  and  the  attacked 
element,  nevertheless  appears  on  the  surface  of  the  non- 
attacked  element. 

This  hydrogen  is  responsible  for  the  weakening  of  our 
cell :  first,  because  it  is  a  very  bad  conductor,  and  thus 
opposes  a  high  resistance  to  the  current ;  and,  second, 
because  it  may  be  itself  attacked  more  readily  than  the 
attackable  element,  so  that  a  reverse  current  is  set  up, 
flowing  in  the  opposite  direction  to  the  one  originally  gen- 
erated. When  a  cell  thus  becomes  weakened,  or  rendered 
inoperative,  it  is  said  to  be  polarized.  It  is  therefore  of 
great  importance  to  prevent  this  polarization  ;  because,  no 
matter  how  high  the  electro-motive  force  of  the  current  at 
the  start,  if  the  current  is  not-  constant  the  battery  is  of 
little  value. 


-IS 


777 /•:  AGE  '>/''  i:Li:i  r 


We  can  now  reeo<'iii/.e  the  68ft6Htill]  ('diidil  ions  of  M  o;oou 
<r:ilv:inic  cell  ;  :IIK|  these  MIT, 

i.  it  should  ha\e  high  electromotive  force. 

"2.  It  should  have  l«>\\  internal  resistance,  so  tint  no 
PIUTiiY  should  he  wasted  within  I  lie  cell. 

3.  It  should  ejve  a  constant  eiirrenl,  :n:d  Ilierefnre 
pol:iri/:ilioii  should  he  prevented  in  it. 

Beyond  these,  MIT  the  further  rci|uircmenls,  that  there 
should  heuoadion  in  the  cell  \vhcn  the  circuit  is  open; 
lliMl  it  should  emit  n<»  di  ^.\><  i  -eeMhlc  fumes;  MIK|.  liiiMlly,  it 
should  he  nuide  of  ehenp  ;ind  l.-istinu,  iiiMtcriMls.  No  one 
f.>iiu  of  cell  fulfils  :ill  these  conditions;  hut,  MS  there  MIT 
verv  IIIMIIV  \Mrieties,  it  is  possihle  to  select  ccrhiin  cells 
MS  especially  :idMptcd  to  pnrliciilMr  purposes. 

<ol\:inic  cells  MTC  usually  dassilied  with  rc;v:m!  to   their 

const  I'licl  ion.    Mild    lo    Ihe    dcpolMri/ino-    Mjj,Tiit     employed. 

Thus    (here    MIT    (I)    ouc-lluid    cells    with    no    depolari/,ei\ 

(•J)  one  lluid  cells  with  solitl  dcpi.lai'i/ei'  or  li<|iii<l  dcpolar- 

i/cr,  and   ('.\ )   1  \\  o  lluid  cells. 

The  simple  cell  of  Volta,  with  ils 
xinc  :»nd  copper  plates  plunged  in  Mcid- 
ulated  water,  is  MII  example  of  NIC  lirsl 
class.  One  of  Ihe  hcsi  forms  is  I  hat 
kno\\n  as  Smce's  hattcry,  in  which 
the  copper  is  repLaced  hy  platinum  or 
plaliui/.ed  silver.  The  rou«>li  suri'Mce 
of  the  platinum  o'ives  up  Ihe  hydro-ren 
bubbles j  :md  so  diminishes  polari/.a- 
tion.  The  ordinary  arrangement  of 
Smee's  cell  is  shown  in  l«'i«j.  I  I.  The 
plate  of  platinum  or  platini/.ed  silver 
is  suspended  from  a  wooden  har  whicn 

sujtports    two    plates   of    amalgamated    /.inc.      Siue,le-lluid 
lotteries  of    the  al>o\e  l\| v    are   siihjccl    to    three   defects: 


n. \  /T/-: /,•)". 


49 


(lirst)  their  electro-motive  force  is  weakened  by  polariza- 
tion, and  they  have  (second)  neither  a  constant  current, 
nor  (third)  a  constant 

To  the  second  class  of  cells 
above  enumerated,  belong  the 
well-known  (In-net  (liquid 
depolarizer)  and  Lcclanche 
(solid  depolarizer)  forms. 
The  Crenet  cell  (Fig.  12), 
or.  as  it  is  sometimes  called, 
the  ••  bottle  battery,"  con- 
tains a  plate  of  zinc  sus- 
pended between  two  plates 
of  carbon.  The  /ine  is  usu- 
ally alllxed  to  a  rod,  so  that 
it  can  be  conveniently  raised 
out  of  the  solution  when  the 
cell  is  not  in  use.  The  liquid 
here  contains  bichromate  of 

potash,  sulphuric  acid,  and  water.  This  solution  chemi- 
cally acts  upon  the  hydrogen  bubbles,  t,,  destroy  them 
while  they  are  in  a  nascent  state.  This  cell  has  a 
electro-motive  force  at  the  lu^inninir,  and  yield*  a 
fill  current. 

The  Leclanche'  cell,  which  is  very  much  used  on 
telephone  lines,  and  which  is  represented  in  Fiu;.  1;;, 
contains  a  carbon  plate,  against  which  are  fastened 
by  rubber  bands  blocks  of  solid  auulomerate.  composed 
of  black  oxide  of  manganese,  carbon,  bisulphate  of 
potassium,  and  .mini  lac.  These  agglomerate  blocks  act 
as  depolarizers.  The  zinc  clement  is  in  the  form  of  a 
rod. 

Complete  depolarization  is  obtained  only  in  two-lluid 
cells,  which  constitute  the  third  class  of  battery  above 


Fig.  12. 


50  THE  AGE   OF  ELECTRICITY. 

noted.     Of   these  the  most  prominent  examples    are  the 
Daniell  and  the  Bnnsen. 

The  Daniell  cell  (Fig.  14)  consists  of  a  containiug- 
vessel  in  which  is  placed  a  porous  earthenware  jar  or  cup. 
Within  the  porous  jar  is  a  plate  of  amalgamated  zinc,  and 
a  dilute  sulphuric  acid.  In  the  outer  vessel  is  a  plate  of 


Fig.  13. 

copper  ;  the  entire  vessel  is  often  itself  made  of  that  metal, 
and  the  liquid  here  is  a  saturated  solution  of  sulphate  of 
copper.  When  the  circuit  is  closed,  the  zinc  is  attacked, 
forming  sulphate  of  zinc,  and  liberating  hydrogen.  Hut 
this  gas,  in  this  cell,  cannot  as  in  other  cells  appear  on  the 
copper  plate  ;  because,  in  meeting  the  sulphate  of  copper, 


THE  GALVANIC  BATTERY. 


51 


the  hydrogen  combines  with  the  sulphur  to  form  sulphuric 
acid,  while  the  copper  is  deposited  in  the  metallic  state 
on  the  copper  plate.  There  is  consequently  no  polariza- 


Fig.  14. 


tion,  and  the  cell  is  constant ;  but  it  has  a  high  internal 
resistance,  and  hence  does  not  give  a  powerful  current. 
The  gravity  cell,  based  on  the  Daniell,  is  very  widely  used 


Fig.  15. 

for  telegraphic  purposes.  Fig.  15  represents  the  Callaud 
form,  in  which  the  zinc,  in  the  form  of  a  cylinder,  is  sus- 
pended by  hooks  from  the  rim  of  the  jar.  The  copper 


THE  AGE  OF  ELECTRICITY. 


Fig.  16. 


element,  a  thin  strip  of  rolled  metal,  rests  on  the  bottom. 
The  solution  of  sulphate  of  copper  is  at  the  bottom  of  the 
jar,  and  remains  there  because  it  is  heavier  than  the  sul- 
phate of  zinc  solution  which  floats  upon  it. 

Bunsen's  battery  is  repre- 
sented in  Fig.  1G,  and  consists 
of  a  glass  vase  V,  in  which  is 
placed  a  cylinder  Z  of  amal- 
gamated zinc,  immersed  in  a 
mixture  of  water  and  sulphuric 
acid.  Within  the  zinc  cylinder 
is  a  porous  jar  D  of  earthen- 
ware, which  contains  a  rod  or 
plate  of  carbon  C  immersed  in 
bichromate  solution  such  as  is 
employed  in  the  Grenet  single- 
fluid  cell  above  described. 

Of  the  different  forms  of  batteries  above  enumerated, 
the  Daniell,  for  its    constancy,  is   usually  taken    as    the 
standard.     Taking   its  electro-motive    force  as  unity,  or 
one  volt,  the  electro-motive  forces  of  the  other  cells  men- 
tioned are  approximately  as  follows  :  — 
Smee,  about  .47  volt. 
Leclanche,  1.48  volt. 
Grenet,  2  volts. 
Bun  sen,  1.9  volt. 

These  forms  are  mentioned  here  merely  as  typical. 
The  actual  number  of  different  galvanic  cells  known  to 
electricians  reaches  into  the  hundreds.  Experiment  with 
the  hope  of  finding  a  cell  which  will  be  more  constant, 
of  higher  electro-motive  force,  or  which  will  consume  a 
cheaper  material  than  zinc,  is  constantly  going  forward. 

As  compared  with  the  steam  boiler,  plus  the  engine  and 
the  dynamo-electric  machine,  as  a  means  of  generating 


THE   GALVANIC  BATTERY.  53 

electricity,  the  battery  is  most  attractive.  It  costs  but  a 
trifle  to  construct ;  it  needs  no  lire,  and  no  attendance : 
these  are  its  advantages.  On  the  other  hand,  zinc  costs 
twenty  times  as  much  as  coal,  and,  other  things  being 
equal,  generates  one-seventh  the  energy. 

Yet  we  know  that  the  consumption  of  zinc  in  the  cell  is 
combustion,  differing  not  essentially  from  the  burning  of 
coal  in  the  furnace.  Why,  we  ask  ourselves,  from  the 
combustion  of  the  expensive  substance  can  we  get  a  direct 
current  of  electricit}',  and  not  from  the  combustion  of  the 
cheaper  material?  Wherever  there  is  oxidation,  there,  in 
some  degree,  an  electric  current  is  generated.  But  oxida- 
tion in  air  is  oxidation  in  the  most  perfect  of  electrical 
insulators.  The  current  will  not  travel  from  the  attacked 
body  to  a  convenient  conductor  via  the  air,  as  it  will  via 
water ;  and  so,  up  to  the  present  time,  we  have  found  no 
way  of  collecting  the  electricity  which  may  be  developed 
in  our  grates  and  furnaces. 

Why,  then,  if  we  can  consume  one  oxidizable  material 
in  the  battery,  cannot  we  consume  another?  If  zinc,  why 
not  carbon?  In  the  Bunsen  cell,  and  in  a  great  many 
others,  carbon  already  enters  into  use  as  the  non-attacked 
element.  Is  it  not  possible  to  use  with  it  some  other  sub- 
stance, which  the  attacking  material  will  not  re-act  upon 
so  readily  as  it  will  upon  carbon  ?  Attempts  in  this  direc- 
tion have  not  been  wanting.  M.  Jablochkoff  has  made  a 
cell  in  which  one  element  is  of  coke,  and  the  other  of  cast 
iron.  His  liquid  is  melted  nitrate  of  potash  or  nitrate  of 
soda.  Here  the  coke,  the  carbon,  is  burned  at  the  ex- 
pense of  the  oxygen  of  the  nitrate,  while  the  cast  iron 
remains  unattacked.  Immense  volumes  of  carbonic  acid 
are  produced.  The  current  yielded  is  powerful.  But  the 
cell  has  no  practical  utility,  save  as  a  mile-post  on  a  road 
toward  perhaps  the  most  important  electrical  invention 


54  THE  AGE  OF  ELECTRICITY. 

that  can  be  made  ;  namely,  the  consumption  of  carbon 
directly  in  the  battery,  at  low  temperatures. 

A  curious  improvement  upon  Jablochkoff's  battery  has 
been  contrived  by  M.  Brard  of  La  Rochelle,  France, 
which  he  calls  an  electro-generative  combustible.  It  is, 
in  fact,  a  fuel  which  produces  electricity ;  or,  rather,  a 
piece  of  prepared  carbon,  which  when  thrown  into  the  lire 
produces  electricity  by  its  combustion.  Each  so-called 
slab  is  about  six  inches  long  by  two  inches  wide  and  an 
inch  thick.  It  is  composed  of  a  prism  of  carbon,  a  prism 
of  nitrate  of  potash,  and  between  these  a  plate  of  asbestos 
which  acts  like  the  porous  partition  in  ordinary  cells. 
The  nitrate  of  potash  is  mixed  with  ashes  to  prevent  too 
rapid  combustion  and  melting,  and  in  this  part  of  the  slab 
is  embedded  a  sheet  of  copper  which  serves  as  one  pole. 
In  the  carbon  are  embedded  several  strips  of  brass  or 
copper  which  are  connected  to  a  single  sheet,  which  forms 
the  other  pole.  It  is  necessary  simply  to  throw  the  brick 
into  the  fire,  previously  attaching  wires  to  the  poles,  to 
obtain  a  continuous  current  for  an  hour  or  two.  The  cur- 
rent of  a  single  slab  will  actuate  an  ordinary  electric  bell. 

The  galvanic  battery,  we  have  defined  as  an  apparatus 
for  converting  the  energy  of  chemical  affinity  into  electri- 
cal energy.  In  most  cases  the  force  of  chemical  affinity 
exerts  itself  as  soon  as  the  ingredients  of  the  cell  are  put 
together ;  in  others,  as  in  the  instance  of  the  Jablochkoff 
carbon  nitrate-of-potash  battery,  the  constituents  of  the 
cell  must  be  heated  before  the  chemical  re-actions  can 
occur.  Of  course,  in  the  latter  case,  the  resulting  elec- 
trical energy  should  represent  not  merely  the  energy  of 
chemical  affinity,  but  also  the  heat  energy  employed  in 
setting  free  the  latter.  In  fact,  however,  the  energy  pro- 
duced is  in  no  wise  commensurate  with  the  energy  ex- 
pended ;  and  all  thermo-galvauic  cells,  so  far  as  now 


THE   GALVANIC  BATTERY. 


55 


known,  are  exceedingly  wasteful.  The  therm o-galvanic 
cell  should  not  be  confounded  with  the  thermo-electric  cell 
or  thermo-pile.  There  is  a  broad  distinction  between  them, 
in  that  the  thermo-galvanic  cell  converts  heat  energy  into 
electrical  energy,  through  the  medium  of  the  energy  of 
chemical  affinity ;  while  there  is  no  perceptible  chemical 
re-action  in  the  thermo-pile,  and  the  heat  applied  is  directly 
converted  into  electricity. 

The  thermo-electric  bat- 
tery  was  discovered  by 
Professor  Seebeck  in  1821. 
He  soldered  together 
a  piece  of  bismuth  and  a 
piece  of  antimony,  con- 
nected their  free  ends  to 
a  galva nometer  which 
would  show  when  a  cur- 
rent passed,  and  then 
heated  a  joint  between  the 
metals.  He  found  that 
when  the  temperature  of 

the  joint  was  greater  than  that  of  the  remainder  of  the 
circuit,  a  current  traversed  the  circuit,  apparently  moving 
from  the  bismuth  to  the  antimony  as  shown  in  Fig.  17; 
whereas,  if  the  joint  was  cooler  than  the  rest  of  the  circuit, 
then  the  current  would  move  the  other  way.  The  electro- 
motive force  thus  set  up  maintains  a  constant  current  so 
long  as  the  excess  of  temperature  of  the  heated  point  is 
kept  up,  heat  being  all  the  while  absorbed  in  order  to 
maintain  the  energy  of  the  current. 

Curiously  enough,  just  as  the  heating  or  the  cooling  of 
the  joint  will  produce  a  current  in  one  or  the  other  direc- 
tion, so  the  passage  of  a  current  through  the  joint  will 
either  heat  or  cool  it.  Thus,  if  a  current  be  conducted 


Fig.  17. 


56  THE  AGE   OF  ELECTRICITY. 

from  bismuth  to  antimony,  the  joint  is  cooled ;  if  it  be  led 
in  the  other  direction,  the  joint  is  heated.  This  peculiar 
phenomenon  was  discovered  by  Peltier  in  1834,  and  is 
known  as  the  Peltier  effect.  Another  remarkable  effect 
was  discovered  by  Sir  William  Thompson.  If  a  copper 
wire  be  heated  at  one  point,  and  cooled  at  another,  a  cur- 
rent passing  through  the  wire  from  the  hot  place  to  the 
cool  place  will  heat  the  wire.  If  the  current  goes  the 
other  way,  the  wire  will  be  cooled ;  but  if  the  wire  be  of 
iron,  then  a  current  from  the  hot  portion  to  the  cold 
portion  causes  cooling. 

In  constructing  a  thermo-electric  pile,  it  is  usual  to  join 
a  number  of  pairs  of  metal,  as  bismuth  and  antimony,  in 
series  so  bent  that  the  alternate  junctions  can  be  heated 
as  shown  in  Fig.  17,  at  A  A  A,  whilst  the  other  set  B  B  B 
are  kept  cool.  The  various  electro-motive  forces  then  act 
all  in  the  same  direction,  and  the  current  is  increased  in 
proportion  to  the  number  of  pairs  of  junctions. 

Numerous  experiments  have  been  made  on  thermo-elec- 
tric batteries,  chiefly  in  France  ;  and  with  an  apparatus  of 
six  thousand  elements,  consuming  some  twenty-two  pounds 
of  coke  per  hour,  two  arc  lights,  equal  to  between  four 
hundred  and  fifty  and  seven  hundred  and  fifty  candles, 
have  been  maintained.  The  trouble  with  the  thermo-pile 
is  its  great  waste  ;  the  amount  of  energy  utilized  being 
only  between  two  and  five  per  cent  of  that  of  the  heat  sup- 
plied. Its  best  application  is  that  made  by  Melloni,  who 
constructed  many  small  pairs  of  antimony  and  bismuth  in 
a  compact  form  for  use  as  a  thermometer.  It  is  employed 
with  a  sensitive  galvanometer,  and  produces  currents  pro- 
portional to  the  difference  of  temperature  between  the  hot- 
ter set  of  junctions  on  one  face  of  the  thermo-pile,  and  the 
cooler  set  on  the  other  face.  If  the  hand,  for  instance, 
be  brought  near  on  the  one  side,  a  current  indicates  its 


THE   GALVANIC  BATTERY.  57 

radiant  power ;  or,  if  a  piece  of  ice  be  brought  near,  a 
current  is  also  indicated,  but  moving  in  the  opposite  direc- 
tion. In  Professor  Tyndall's  admirable  series  of  lectures 
on  "  Heat  as  a  Mode  of  Motion,"  this  instrument  is  con- 
stantly experimentally  employed  to  show  minute  differ- 
ences of  temperature.  It  has  been  proposed  to  utilize  the 
waste  heat  of  furnace-flues  by  surrounding  them  with 
thermo-electric  elements  ;  and  the  reverse  process  has  also 
been  suggested,  of  making  stoves  the  casing  of  which 
generates  electricity,  while  radiators  diffuse  the  uncon- 
verted heat  for  purposes  of  warmth. 

In  the  preceding  chapters  we  have  seen  that  the  dis- 
charge of  an  electric  machine  or  of  a  Leyden-jar  is  a  min- 
iature lightning  flash.  The  discharge  of  a  galvanic  cell, 
on  the  other  hand,  is  continuous,  and  may  flow  over  a 
long  period  of  time.  The  so-called  static  discharge  may 
be  compared  to  the  sudden  explosion  of  dynamite  ;  the 
so-called  dynamic  discharge  or  current,  to  the  gradual 
flow  of  steam  or  water.  Both  are  electrical  discharges, 
and  there  is  no  inherent  difference  in  the  electricity  mani- 
fested ;  although  even  to  suppose  such  a  difference  in- 
volves the  conception  of  electricity  as  a  corporeal  thing, 
like  water,  which  is  not  proved.  So-called  static  electri- 
city is  simply  electricity  of  little  strength,  but  of  enormous 
pressure.  Dynamic  or  galvanic  electricity  has  immense 
strength,  but  little  pressure.  To  borrow  Professor  Tyn- 
dall's illustration  :  a  cubic  inch  of  air,  if  compressed  with 
sufficient  power,  may  be  able  to  rupture  a  very  rigid  en- 
velope ;  while  a  cubic  yard  of  air,  if  not  so  compressed, 
may  exert  but  a  feeble  pressure  upon  the  surface  which 
bounds  it.  Static  or  frictional  electricity  is  in  a  con- 
dition analogous  to  compressed  air:  its  pressure,  its 
electro-motive  force,  is  great.  Galvanic  or  dynamic 
electricity  resembles  the  uncompressed  air :  there  is  a 


58  THE  AGE   OF  ELECTRICITY. 

great  deal  more  of  it,  but  its  pressure  is  comparatively 
minute. 

The  immense  strength  of  current  of  the  galvanic  cell, 
and  consequent  quantity  of  electricity  yielded  thereby,  as 
compared  with  the  infinitesimal  quantity  and  enormous 
pressure  of  the  static  discharge,  was  illustrated  in  a 
remarkable  manner  by  Professor  Faraday.  As  will  be 
explained  hereafter,  an  electrical  current  when  conducted 
into  water  will  decompose  the  same,  tearing  asunder  the 
hydrogen  and  oxygen  molecules,  and  of  course  exerting 
energy  to  effect  this  separation.  The  quantity-of  current 
necessary  to  decompose  a  grain  of  water  is  very  small. 
It  measures  3.13  amperes  ;  and  some  idea  of  what  it  can 
do  will  be  obtained  from  the  fact  that  it  should  keep  a 
platinum  wire  TJT  of  an  inch  in  diameter  red  hot  for  three 
and  three-quarters  minutes.  In  order  to  effect  this  same 
decomposition  by  static  electricity,  there  would  be  required 
eight  hundred  thousand  charges  of  fifteen  large  Leyden- 
jars  :  each  charge  would  be  fully  capable  of  killing  a  rat, 
and  if  all  of  the  charges  could  be  accumulated  into  one, 
the  result  would  be  a  great  flash  of  lightning.  Faraday 
estimated  the  electricity  due  to  the  chemical  action  of  a 
single  grain  of  water  on  four  grains  of  zinc  to  be  equal 
in  quantity  to  that  of  a  powerful  thunder-storm. 

By  linking  cells  together,  as  has  already  been  described, 
we  can  increase  the  pressure  of  the  galvanic  current,  and 
make  it  more  nearly  approach  that  of  the  fractional  or  static 
current.  Professor  Tyndall,  however,  states  that  it  requires 
a  battery  of  more  than  a  thousand  cells  to  make  the  gal- 
vanic current  jump  over  an  interval  of  air  one-thousandth 
of  an  inch  in  length.  An  electric  machine  of  moderate 
power,  and  furnished  with  a  suitable  conductor,  is  com- 
petent to  urge  its  current  across  an  interval  ten  thousand 
times  as  great  as  this.  The  magnetic  needle  will  respond 


THE   GALVANIC  BATTERY.  59 

to,  and  show  by  its  deflection,  the  passage  of  an  almost 
infinitesimally  small  galvanic  current ;  but  it  is  only  by 
the  aid  of  arrangements  for  multiplying  the  effect  that  the 
discharge  of  a  large  static  electrical  machine  is  enabled  to 
produce  any  deflection.  With  11,000  cells,  the  aggregate 
electro-motive  force  of  which  was  11,330  volts,  Mr.  War- 
ren de  la  Rue  succeeded  in  obtaining  a  spark  but  0.62  inch 
in  length.  On  this  basis,  the  electro-motive  force  of  a 
lightning  flash  a  mile  long  should  be  over  three  and  one- 
half  million  volts. 

We  have  already  noted  the  fact,  that  wherever  a  chemi- 
cal re-action  exists  between  conducting  substances,  an 
electric  current  is  produced.  This  re-action  in  a  great 
many  instances  results  from  oxidation,  the  combining  of 
the  oxygen  of  the  liquid,  usually  with  the  substance  of  the 
attacked  element. 

A  very  ingenious  form  of  gas  battery,  invented  by  Sir 
W.  Grove,  contains  platinum  elements  in  contact  respec- 
tively with  hydrogen  and  oxygen  gases.  These  elements 
enter  water ;  and  if  they  are  joined  by  a  wire,  a  current 
apparently  flows  from  the  hydrogen,  through  the  water 
in  which  the  ends  of  the  elements  enter,  to  the  oxygen. 
The  hydrogen  plays  the  part  of  a  zinc  plate,  being 
oxidized  by  the  water ;  and  the  hydrogen  set  free  ap- 
pears at  the  positive  element  (oxygen),  and  combines 
with  it. 

Various  cells  have  been  devised  with  the  object  of 
utilizing  the  oxygen  of  the  air  for  depolarizing  purposes. 
Thus  currents  of  air  are  sometimes  pumped  into  the  cell, 
and  against  the  plate  on  which  the  hydrogen  is  formed  ; 
and  various  cells  have  been  devised,  in  which  the  polarized 
plate  is  in  the  form  of  an  endless  belt,  a  wheel,  or  a  series 
of  radial  spokes.  The  wheel  or-  belt  is  revolved  so  as  to 
be  partly  in  and  partly  out  of  the  cell ;  so  that  a  portion 


60  THE  AGE   OF  ELECTRICITY. 

of  it  is  always  active  while  the  remainder  is  in  the  air,  the 
hydrogen  then  escaping. 

Jablochkoff's  auto-accumulator  is  a  cell  remarkable  for 
its  small  size,  light  weight,  low  cost,  and  freedom  from 
deleterious  fumes.  It  consists  of  a  shallow  vessel  of  hard 
carbon,  in  which  are  placed  scraps  of  metal,  such  us  iron, 
zinc,  or  sodium  amalgam.  Above  the  metal  is  a  thickness 
of  sawdust,  or  a  piece  of  coarse  cloth,  impregnated  with 
chloride  of  calcium.  Upon  the  cloth  are  laid  hollow  sticks 
of  porous  carbon.  The  whole  forms  a  cell  four  inches 
square  and  one  inch  high.  The  metal  scraps  and  the 
carbon  vessel  form  a  couple,  the  carbon  being  polarized 
or  charged  with  hydrogen.  This  carbon  is  in  electrical 
circuit  with  the  upper  porous  carbons,  which  absorb  oxy- 
gen from  the  air.  Thus  we  have  two  surfaces  of  carbon, 
one  charged  with  hydrogen  and  the  other  with  oxygen  ; 
and  these  constitute  the  elements  of  the  cell.  As  the  cur- 
rent flows,  the  oxygen  and  hydrogen  generally  combine  ; 
and  the  action  continues  until  the  supply  of  one  or  the 
other  of  them  is  practically  exhausted.  Then,  if  the  cir- 
cuit be  broken,  a  recuperative  process  immediately  com- 
mences :  the  hydrogen  is  evolved  from  the  metal,  and 
attaches  itself  to  the  one  carbon  plate  ;  while  the  other 
electrode  fills  its  interstices  again  with  oxygen,  which  will 
be  drawn  out  when  the  current  commences  to  circulate. 
And  so  the  process  goes  on,  —  action  following  rest,  and 
rest  following  action,  as  long  as  the  supply  of  metal  is  not 
exhausted,  and  there  remains  a  small  quantity  of  moisture 
required  for  its  oxidation.  Five  of  these  cells  in  series 
will  operate  a  five-candle-power  lamp  for  an  hour,  the  fila- 
ment being  still  bright  red  at  the  end  of  that  time.  This 
cell  is  believed  to  be  of  great  promise  as  a  means  of  sup- 
plying current  for  domestic  electric  lighting. 

Another  curious   atmospheric  battery,   devised    by  M. 


THE  GALVANIC  BATTERY.  61 

Jablochkoff,  consists  simply  of  a  small  rod  of  sodium, 
squeezed  into  contact  with  an  amalgamated  copper  wire, 
and  flattened.  This  is  wrapped  in  paper,  and  secured  to 
a  plate  of  porous  carbon.  No  liquid  is  used,  the  moisture 
of  the  air  settling  on  the  oxidized  surface  of  the  sodium 
being  sufficient. 

A  battery  which  appears  to  be  a  decided  step  in  the 
direction  of  producing  electricity  from  the  oxidation  of 
coal,  without  the  intervention  of  the  steam-engine,  was  de- 
vised in  1885  by  Mr.  J.  A.  Kendall,  an  English  electrician. 
Its  operation  is  based  upon  the  well-known  phenomenon  of 
hydrogen  passing  through  platinum  at  a  red  heat ;  two 
platinum  plates  being  used  as  the  poles,  one  exposed  to 
hydrogen,  and  the  other  to  oxygen.  These  plates  are 
arranged  in  concentric  tubes,  closed  at  one  end,  and  are 
separated  by  a  fluid  medium  of  fused  glass.  Hydrogen 
gas  is  continuously  supplied  to  the  inner  platinum  tube, 
while  the  entire  apparatus  is  maintained  at  a  high  tem- 
perature by  means  of  a  furnace.  The  absorption  of 
hydrogen  by  the  platinum  is  accompanied  by  electric  gen- 
eration, and  the  current  is  led  away  by  wires  connected  to 
the  platinum  tubes.  The  inventor  has  estimated  that  a 
ton  of  coke  used  in  heating  the  battery,  including  the 
hydrogen-producer,  will  give  at  least  three  times  the  elec- 
trical energy  that  would  be  produced  by  the  same  quantity 
of  coke  used  in  working  a  steam-engine  and  dynamo. 

There  are  a  great  many  other  forms  of  galvanic  cell, 
and  new  ones  are  constantly  appearing.  Most  of  them 
are  mere  modifications  of  certain  general  types :  others, 
and  especially  those  which  involve  novel  modes  of  pre- 
venting polarization,  or  which  amount  to  real  advances 
in  the  direction  of  consuming  carbon,  or  utilizing  the  oxy- 
gen of  the  atmosphere,  are  of  great  scientific  interest. 
The  subject  is  a  most  inviting  one  to  inventors. 


62  THE  AGE   OF  ELECTRICITY. 

The  battery  of  the  future  —  and  it  will  be  the  greatest 
of  electrical  wonders,  when  it  is  invented  —  will  simply 
reproduce  the  Conditions  existing  in  every  household  grate  ; 
that  is,  it  will  burn  coal,  by  the  aid  of  the  air,  to  produce 
electricity.  At  the  present  time,  however,  there  are  sev- 
eral forms  of  battery  which  are  worth  noting  as  electrical 
curiosities.  One  inventor  boldly  grasps  the  ocean,  and 
utilizes  it  as  his  conducting  liquid.  Of  "  earth  batteries," 
the  globe  we  live  on  forms  a  part.  These  have  been  used 
for  driving  clocks,  and  many  people  have  supposed  that 
in  some  way  electricity  is  drawn  directly  out  of  the  ground. 
Earth  batteries,  however,  simply  consist  of  plates  of  dif- 
ferent metals,  usually  zinc  and  copper,  which  are  buried 
at  a  little  distance  apart  in  moist  soil,  the  latter  acting 
like  the  liquid  in  an  ordinary  cell.  They  have  a  high 
resistance,  and  low  electro-motive  force.  The  best  place 
for  the  zinc  plate  is  under  a  stable,  where  saline  liquids 
permeate  the  ground.  One  inventor  thought  he  had  made 
a  tremendous  discovery  in  recognizing  that  the  lead  water- 
pipes  and  the  iron  gas-mains  buried  under  city  streets 
constitute  a  huge  earth  battery,  from  which  unlimited 
electricity  might  be  drawn  to  light  the  city.  The  fact  that 
a  battery  is  there  is  true  enough  :  but,  unfortunately,  the 
attackable  substance  of  the  couple  is  the  iron  gas-main, 
which  would  be  surely  consumed  ;  and,  as  the  plan  did 
not  contemplate  any  remuneration  to  gas-companies  for 
gas  lost  by  leakage,  it  failed  to  come  into  practical  use. 

M.  Duchemin  has  proposed  to  use  the  ocean  as  the 
liquid  in  his  battery,  and  submerge  in  the  sea  plates  of 
zinc  and  carbon  attached  to  a  floating  body.  The  main 
object  of  this  battery  was  the  preservation  of  the  iron 
hulls  of  vessels,  or  the  iron  buoys,  from  oxidation.  Some 
experiments  were  made  on  a  small  scale,  which  apparently 
demonstrated  that  it  was  possible  in  this  way  to  preserve 


THE   GALVANIC  BATTERY.  63 

a  surface  of  iron  eighteen  times  larger  than  that  of  the 
zinc  electrode  used.  The  investigations  were  interrupted 
by  the  outbreak  of  the  Franco-German  war,  and  have  not 
been  resumed.  A  somewhat  similar  idea  was  proposed 
many  years  earlier,  by  Sir  Humphry  Davy,  who  suggested 
the  protection  of  the  copper  sheathing  of  vessels,  by  means 
of  a  communicating  sheet  of  zinc  immersed  in  the  sea.  It 
was  found  that  an  extent  of  zinc  surface,  one  hundred 
and  fifty  times  less  than  that  of  the  copper,  was  suffi- 
cient to  protect  the  latter ;  but  the  plan  was  abandoned 
for  the  reason  that  certain  salts  contained  in  the  sea-water 
were  decomposed,  and  the  resulting  earthy  oxides  depos- 
ited themselves  on  the  copper,  roughening  the  surface, 
and  rendering  the  same  particularly  inviting  to  barnacles, 
which  attached  themselves  in  great  numbers,  and  so  ma- 
terially impeded  the  speed  of  the  vessel. 

It  may  be  mentioned  here,  that  efforts  have  been  made 
of  late  years  to  remove  barnacles  from  ships'  bottoms  by 
powerful  currents  led  to  the  copper  from  dynamo-electric 
machines,  thence  passing  to  the  water.  The  current 
seriously  incommoded  the  barnacles,  which  made  such 
efforts  as  lie  within  the  limited  capacity  of  the  clam,  to 
get  out  of  their  shells  ;  but,  Nature  not  having  provided 
them  with  suitable  means  for  this  purpose,  they  remained, 
and  submitted  to  the  disturbance  with  their  usual  equa- 
nimity, possibly  cheered  by  the  knowledge  that  on  the 
whole  the  experiment  was  a  failure. 

Probably  the  largest  galvanic  battery  ever  made  is  that 
used  in  the  Royal  Institution  in  London.  It  consists  of 
14,400  cells  of  chloride  of  silver  and  zinc  elements.  It  is 
estimated  that  a  lightning  flash  a  mile  long  could  be  pro- 
duced by  243  such  batteries. 

The  battery  which  will  last- the  longest  is  the  dry  pile 
devised  by  Zamboni.  This  consists  of  a  number  of  paper 


64  THE  AGE   OF  ELECTRICITY. 

disks,  coated  with  zinc  foil  on  one  side  and  with  an  oxide 
of  manganese  on  the  other,  piled  upon  one  another,  to  the 
number  of  many  thousands,  in  a  glass  tube.  The  electro- 
motive force  is  great,  and  a  good  pile  will  yield  sparks. 
The  current  is  very  weak,  but  it  lasts  an  extraordinary 
length  of  time.  In  the  Clarendon  Library  at  Oxford, 
there  is  a  pile,  the  poles  of  which  are  two  metal  bells  ; 
between  them  is  hung  a  small  brass  ball,  which,  by  oscil- 
lating to  and  fro,  slowly  discharges  the  electricity.  It 
has  been  continuously  ringing  the  bells  for  over  forty 
years. 

One  of  the  most  curious  alleged  discoveries  concerning 
the  galvanic  battery  was  that  of  Mr.  Arnold  Crosse,  who 
in  the  early  part  of  the  present  century  announced  the 
extraordinary  fact  that  living  insects  were  generated  in 
the  cell.  He  stated,  that  while  endeavoring  to  deposit 
crystals  of  silica  on  a  lump  of  stone,  by  the  agency  of  the 
current,  he  noticed,  after  the  experiment  had  continued 
for  a  fortnight,  whitish  specks  on  the  stone,  which  at  the 
end  of  the  twenty-eighth  day  assumed  the  appearance  of 
insects,  standing  erect  on  the  bristles  which  formed  their 
tails,  and  distinctly  moving  their  legs.  The  experimenter 
was  greatly  astonished.  Instead  of  a  mineral,  for  which 
be  had  looked  as  the  result  of  his  experiment,  he  had 
found  an  animal,  alive  and  kicking.  It  was  plain  these 
were  no  mere  appearances ;  for  in  a  few  days  they  de- 
tached themselves  from  the  stone,  and  began  to  move 
about.  They  were,  to  be  sure,  not  creatures  of  a  very 
inviting  and  attractive  character ;  for  they  belonged  ap- 
parently to  the  genus  acarus,  which  includes  some  of  the 
most  disagreeable  parasites  of  the  animal  body.  But  they 
continued  to  increase,  and  in  the  course  of  a  few  weeks 
hundreds  made  their  appearance.  Crosse  himself  hesi- 
tated to  believe  that  spontaneous  generation  could  attend 


THE   GALVANIC  BATTERY.  65 

any  action  of  electricity,  and  conjectured  that  bis  cell  was 
simply  a  favorable  place  for  tbe  hatching  of  the  ova  of 
the  insects  existing  in  the  atmosphere.  He  and  others  at 
the  time  made  many  experiments  intended  to  preclude  the 
possibility  of  these  ova  being  present,  but  the  insects 
continued  to  appear.  The  phenomenon  made  a  great 
sensation.  Despite  the  fact  of  Crosse's  own  hesitancy 
in  asserting  that  he  could  produce  life,  others  flatly  main- 
tained the  possibility.  At  the  opposite  extreme,  were 
those  who  attacked  Crosse  for  impiety.  If  he  began  by 
creating  animals  by  electrical  power,  no  matter  of  how 
inferior  sort,  who  could  tell  where  he  might  stop?  He 
was  called  a  "  disturber  of  the  peace  of  families,"  and  a 
"  reviler  of  religion." 

The  French  Academy  of  Sciences,  however,  on  receipt 
of  a  phial  of  the  mysterious  insects,  treated  the  whole 
matter  as  unworthy  of  serious  consideration  ;  and  one 
member  individually  pointed  out  that  the  means  employed 
by  Crosse  simply  excited  and  favored  the  germination  of 
the  ova  which  must  have  been  present.  Many  years  later 
(1859),  Professor  Schulze  in  Germany  repeated  Crosse's 
experiments,  aided  by  more  modern  knowledge  of  minute 
organisms,  and  modes  of  sterilization,  and  showed  con- 
clusively that  none  were  generated.  The  controversy  had 
then  continued  for  nearly  half  a  century. 

Among  other  remarkable  ideas  concerning  the  galvanic 
battery,  it  has  been  suggested,  that,  wherever  two  flavors 
are  habitually  formed  in  cooking  and  eating,  the  reason 
why  they  mutually  improve  each  other  is  because  a  certain 
amount  of  electric  action  is  set  up  between  the  sub- 
stances employed  to  produce  them.  Mr.  Edwin  Smith, 
M.A.,  has  conducted  quite  an  extended  series  of  experi- 
ments based  on  this  theory  ;  and  has  used  as  elements  in 
a  galvanic  cell,  pairs  of  eatables  which  generally  go  to- 


66  THE  AGE   OF  ELECTRICITY. 

gether,  such  as  pepper  and  salt,  coffee  and  sugar,  almonds 
and  raisins.  He  states  that  he  found  a  voltaic  current, 
more  or  less  strong,  excited  in  every  instance,  and  that 
bitters  and  sweets,  pungents  and  salts,  or  bitters  and 
acids,  generally  appear  to  furnish  true  voltaic  couples, 
doubtless  in  consequence  of  the  mutual  action  of  some 
alkaloid  salt,  and  an  acid  or  its  equivalent.  Mr.  Smith 
gives  quite  a  long  list  of  substances  tested.  Among  his 
couples  are  tea  and  sugar,  raw  potato  and  lemon- juice, 
nutmeg  and  sugar,  horse-radish  and  table  salt,  onion  and 
beet-root,  vanilla  and  sugar,  starch  and  iodine,  and 
tobacco  and  tartaric  acid.  The  substance  firs't  named  in 
each  couple  takes  the  place  of  the  zinc,  or  attacked 
element,  in  the  cell. 

Mr.  Smith  suggests  that  the  rationale  of  the  right 
blending  of  flavors  "  might  be  found  partly,  no  doubt, 
in  chemistry,  but  partly  also  in  galvanism." 

One  of  the  most  curious  batteries  is  that  devised  by 
Sauer,  which  appears  to  act  only  in  the  sunlight.  It 
consists  of  a  glass  vessel  containing  a  solution  of  table 
salt  and  sulphate  of  copper  in  water ;  within  is  a  porous 
cell  containing  mercury.  One  element  is  of  platinum, 
and  is  immersed  in  the  mercury :  the  other  is  sulphide  of 
silver,  and  is  placed  in  the  salt  solution.  Both  elements 
are  connected  to  a  galvanometer.  When  the  battery  is 
placed  in  the  sunlight,  the  needle  is  deflected  to  a  certain 
point,  and  the  sulphide  of  silver  is  found  to  be  the  negative 
pole.  The  action  of  the  battery  depends  on  the  effect  of 
the  chloride  of  copper  upon  the  mercury.  Sub-chloride 
is  formed,  and  reduces  the  sulphide  of  silver ;  but  this 
can  take  place  only  by  the  aid  of  sunlight. 

For  the  heavy  work  of  electric  lighting,  or  the  driving 
of  electro- motors,  batteries  are  superseded  by  dynamo- 
electric  machines,  for  economical  reasons  already  pointed 


THE  GALVANIC  BATTERY.  67 

out;  but  where  large  expenditure  of  energy  is  not  re- 
quired, as  in  the  telegraph  and  telephone,  batteries  find 
a  wide  utilization.  Ultimately  they  will  displace  the 
dynamo,  and  in  time  the  steam-boiler.  To  make  them  do 
this,  is  the  great  electrical  problem  of  the  century. 


68  THE  AGE  OF  ELECTRICITY. 


CHAPTER    VI. 

THE     ELECTRO-MAGNET,     AND      THE      CONVERSION      OF      ELEC- 
TRICITY   INTO    MAGNETISM. 

THE  tide  of  a  great  river  moving  to  the  sea  is  the 
embodiment  of  mighty  volume.  The  mountain  stream, 
albeit  a  mere  thread  of  water  leaping  down  from  rock  to 
rock,  conve}rs  to  us  the  idea  of  intense  energy.  The 
volume  of  the  river,  the  force  of  the  torrent,  unite  in  the 
great  cataract.  All  of  these  conditions  find  their  parallels 
in  the  electrical  current.  From  the  galvanic  battery  flows 
the  slow  and  steady  river ;  from  the  electric  machine, 
the  swift  but  slender  torrent ;  and  from  the  dynamo,  the 
Niagara. 

And,  as  we  have  seen,  the  electrical  current  moving  in 
its  path  is  governed  by  laws  similar  to  those  which  control 
water  flowing  in  its  channel.  We  can  contract  the  area 
of  the  conduit  to  diminish,  or  enlarge  it  to  increase,  the 
flow.  We  can  augment  or  decrease  the  pressure  of  either 
water  or  electricity,  and  so  send  more  or  less  through  the 
appointed  path  in  a  given  time. 

A  step  farther,  and  the  analogy  fails.  Water  acts 
directly  only  upon  objects  in  it  or  on  it.  It  may  float  a 
vessel,  or  turn  a  wheel,  or  break  down  barriers  ;  but  the 
mightiest  flood  cannot  influence  a  grain  of  iron  to  move 
one  way  or  the  other,  if  a  few  feet  of  air  intervene.  Sup- 
pose a  current  of  water  did  have  all  the  properties  of  an 


THE  ELECTRO-MAGNET.  69 

electrical  current :  what  might  happen  ?  Perhaps,  around 
and  above  every  stream,  there  would  be  a  viewless  atmos- 
phere which  we  could  not  penetrate  ;  an  atmosphere  in 
which  the  laws  of  gravity  affecting  iron  and  steel  would 
be  set  at  naught,  in  which  every  iron  bar  would  be  a  mag- 
net placing  itself  across  the  flood,  —  a  most  strange  and 
mysterious  medium,  in  which  things  of  iron  and  steel 
would  arrange  themselves  in  curious  cuives,  whorls  and 
whirlpools  and  vortices  of  iron  ;  a  field  of  strains  and 
stresses  in  something  not  the  air  yet  in  and  with  the  air, 
of  lines  of  forces  without  breadth  and  unending. 

This  sounds  fantastic  when  spoken  of  water.  But  it  is 
true  of  two  natural  phenomena, — a  conductor  through 
which  an  electrical  current  is  passing,  and  the  magnet. 
Around  the  wire  through  which  electricity  is  passing,  and 
in  front  of  the  poles  of  a  magnet,  exists  this  strange 
aura ;  not  in  imagination,  but  in  fact,  for  we  can  make  it 
visible. 

First,  however,  let  us  recall  something  about  magnets 
in  general. 

Ages  ago,  in  Magnesia  in  Asia  Minor,  were  found  cer- 
tain hard  black  stones  which  possessed  the  remarkable 
property  of  attracting  to  themselves  bits  of  iron  and  steel. 
These  the  ancients  called  magnets,  from  the  name  of  the 
locality  in  which  they  were  found.  And  as  their  behavior 
was  altogether  incomprehensible,  the  ancients,  in  accord- 
ance with  their  usual  way  of  dealing  with  things  which 
they  did  not  understand,  disposed  of  the  problem  very 
easily  by  ascribing  the  phenomenon  to  the  supernatural 
powers.  It  is  a  little  odd,  by  the  way,  that  pretty  much 
every  thing  which  the  ancients  used  to  attribute  to  genii 
and  spirits  —  because  unintelligible —  is  unhesitatingly  as- 
cribed by  a  large  section  of  their  posterity  to  "electri- 
city ; "  the  mere  mention  of  the  word  being  quite  sufficient 


70  THE  AGE   OF  ELECTRICITY. 

to  account  for  any  thing  out  of  the  common  run.  from 
rheumatism  to  red  sunsets. 

The  knowledge  of  the  ancients  about  the  magnet  seems 
to  have  stopped  with  the  fact  of  its  attractive  power.  The 
Orientals,  with  characteristic  largeness  of  imagination, 
were  not  slow  to  conceive  of  the  tremendous  things  which 
huge  magnets  might  do.  Who  does  not  remember  the 
story  of  the  third  calendar  in  the  "Arabian  Nights," 
wherein  the  story-teller  recounts  the  remarkable  fate  which 
befell  his  ship  ? 

"  A  sailor  from  the  mast-head  gave  notice  that  he  saw 
something  which  had  the  appearance  of  land,  but  looked 
uncommonly  black.  The  pilot,  on  this  report,  expressed 
the  utmost  consternation.  '  We  are  lost ! '  said  he  :  '  the 
tempest  has  driven  us  within  the  influence  of  the  black 
mountain,  which  is  a  rock  of  adamant,  and  at  this  lime 
its  attraction  draws  us  toward  it :  to-morrow  we  shall 
approach  so  near  that  the  iron  and  nails  will  be  drawn  out 
of  the  ship,  which  of  course  must  fall  to  pieces  ;  and  as 
the  mountain  is  entirely  inaccessible,  we  must  all  perish/ 
This  account  was  too  true.  The  next  day,  as  we  drew 
near  the  mountain,  the  iron  all  flew  out  of  the  ship :  it  fell 
to  pieces,  and  the  whole  crew  perished  in  my  sight." 

For  a  great  many  centuries,  the  world  knew  simply  that 
magnets  would  attract  iron.  Then  somebody  —  tradition 
says  the  Chinese  (which  is  convenient,  because  every- 
body knows  they  were  civilized  ages  ago,  and  if  they  did 
not  have  modern  improvements  then,  no  one  can  dispute 
to  the  contrary)  —  hung  up  a  magnet  by  a  thread,  and 
discovered  that  it  pointed  north  and  south.  After  that  it 
was  called  the  loadstone  (leading  stone),  and  the  mari- 
ner's compass  came  into  existence.  Now  we  know  the 
magnet  as  an  ore  of  iron,  miueralogically  termed  magnet- 
ite, and  chemically  Fe8  O4. 


THE  ELECTEO-MAGNET.  71 

This  knowledge,  however,  useful  as  it  is,  has  not  pre- 
vented people  from  trying  to  press  the  magnet  into  service 
as  a  means  of  solving  that  long- vexed  problem,  of  lifting 
one's  self  over  a  fence  by  one's  own  boot-straps.  Where- 
fore they  have  invented  —  or  rather  failed  to  invent  — 
magnetic  motors,  —  not  electro-magnetic  motors,  which 
are  quite  another  thing,  but  motors  depending  on  the 
constant  attraction  of  permanent  magnets.  Every  once 
in  a  while,  some  one  announces  the  accomplishment  of 
this  feat,  which  primarily  depends  on  cutting  off  the  at- 
traction of  the  magnet  by  causing  the  latter  to  move  some- 
thing in  the  way  of  a  screen  between  its  own  pole  and 
the  thing  attracted.  Unfortunately,  magnetic  attraction 
refuses  to  be  cut  off  in  any  such  way.  It  is  as  stubborn  in 
this  respect  as  the  attraction  of  gravity,  which  it  very 
much  resembles. 

In  that  same  famous  work  which  began  the  modern 
science  of  electricity  in  1600, — Dr.  Gilbert's  "  De  Mag- 
nete,"  —  it  was  announced  that  the  attractive  power  of 
a  magnet,  when  in  elongated  form,  resides  at  the  ends. 
These,  Gilbert  called  the  poles  ;  and  he  also  pointed  out 
that  the  intermediate  region  attracted  iron-filings  less 
strongly,  while  midway  between  the  poles  there  was  no 
attraction  at  all.  Every  magnet,  large  or  small,  has  these 
poles  :  they  are  inseparable.  We  may  grind  a  magnet 
into  powder :  every  grain  will  be  an  independent  magnet, 
having  its  opposite  poles.  Furthermore,  just  as  there  ap- 
pear to  be  two  kinds  of  electricity,  —  high  potential  and 
low  potential,  or  positive  and  negative,  — so  these  two  poles 
appear  to  have  opposite  characters  ;  one  tending  to  move  to 
the  north,  the  other  to  the  south.  Hence  the  poles  are  com- 
monly called,  respectively,  the  north  and  the  south  poles. 
When  the  poles  of  two  magnets  are  brought  together,  like 
poles  always  repel,  while  unlike  poles  attract  each  other. 


72  THE  AGE   OF  ELECTRICITY. 

To  Gilbert  is  due  the  distinction  between  magnets  and 
magnetic  bodies.  A  magnetic  body  is  a  body  capable  of 
being  magnetized,  —  such  as  a  piece  of  iron.  Either  pole 
of  a  magnet  will  attract  a  magnetic  body  ;  but  two  mag- 
nets will  attract  or  repel  each  other,  according  as  unlike 
or  like  poles  are  presented.  Gilbert  also  made  the  ex- 
traordinary discovery  that  the  earth  is  a  huge  magnet ; 
that  its  poles  coincide,  nearly,  with  the  geographical  North 
and  South  Poles  ;  and  that  therefore  it  causes  the  freely 
suspended  magnet  which  forms  the  compass  needle  to 
place  itself  in  a  north-and-south  position. 

And  now  we  reach  a  fact  about  magnets  which  is  be- 
wildering, because  it  tends  to  upset  all  our  notions  about 
time.  If  we  present  a  magnet  to  a  bit  of  iron,  we  see  the 
iron  attracted  apparently  instantly.  We  should  be  ready 
to  assert,  by  all  the  evidences  of  our  senses,  that  abso- 
lutely nothing  could  happen  between  the  instant  the  mag- 
net is  presented  and  the  instant  the  iron  is  attracted.  Yet 
something  does  happen.  Before  that  magnet  can  attract 
the  iron,  —  while  the  iron  is  yet  distant  from  it,  —  it  must 
alter  the  whole  magnetic  state  of  the  iron  mass.  The 
magnet  must  induce,  on  the  end  of  the  iron  nearest  it,  a 
pole  of  opposite  name  to  the  pole  presented ;  and  at  the 
farther  end  of  the  iron,  a  pole  of  the  same  name.  In 
other  words,  it  must  convert  the  magnetic  body  into  a 
magnet.  Having  done  that,  it  repels  one  end,  and  at- 
tracts the  other.  But  this  is  done  before  the  attraction 
begins  ;  but  in  what  period  of  time  we  do  not  know,  nor 
could  we  form  the  faintest  conception  of  its  duration  if 
we  did. 

Why  does  a  magnet  act  in  this  way?  What  is  the  mys- 
terious atmosphere  surrounding  it,  which  makes  it  repel 
or  attract  bodies,  or  convert  other  bodies  into  magnets? 
There  is  a  theory,  —  a  very  learned  one, — which  is  al- 


THE  ELECTRO-NAG  NET.  73 

together  too  deep  for  these  pages,  so  it  is  left  out ;  but, 
without  going  into  that,  we  can  see  for  ourselves  the 
effects  of  this  atmosphere,  in  a  very  satisfactory  way. 


If  we  take  an  ordinary  bar  magnet,  and  place  a  piece 
of  paper  —  or,  better,  glass  —  over  one  of  its  poles,  and 
sprinkle  finely  sifted  iron-filings  on  the  glass,  we  shall  see 
these  filings  arrange  themselves  in  curious  curves,  appar- 


Fig.  19. 


ently  radiating  from  the  pole,  as  in  Fig.  18.  If  we  sub- 
stitute for  the  bar  magnet  a  horse-shoe  magnet,  and  place 
the  glass  over  both  poles,  we  shall  find  that  the  lines 


74 


THE  AGE  OF  ELECTRICITY. 


diverge  nearly  radially  from  each  pole,  and  curve  around 
to  meet  the  opposite  pole,  as  in  Fig.  19.  If  we  take  two 
horse-shoe  magnets,  and  place  like  poles  facing  each  other, 


then  the  filings  curve  away  as  if  repelling  each  other,  as  in 
Fig.  20  :  on  the  other  hand,  if  we  bring  opposite  poles  of 
the  magnets  into  proximity,  then  the  filings  curve  around 
from  one  pole  to  the  other.  The  actual  appearance  of  the 


Fig.  21. 


iron-filings 


iron-filings   is   here  shown,  in  Fig.   21.     The 
represented  were  dusted  over  glass  plates   supported   on 
the  poles  of  the  magnets  ;    and  when  they  had  assumed 


THE  ELECTEO-MAGNET.  75 

the  positions  clue  to  the  magnetic  influence,  they  were 
fixed  in  place  by  an  adhesive  substance,  and  the  plates 
were  used  as  photographic  negatives,  whence  the  engrav- 
ings were  produced. 

Now,  what  does  all  this  mean?  Simply,  that  the  mag- 
net is  telling  its  own  story,  —  writing  it,  in  fact,  for  us  to 
read.  We  know  perfectly  well  that  iron-filings  will  no 
more  arrange  themselves  in  rows  or  curves,  of  their  own 
volition,  than  books  will  place  themselves  in  rows  on 
shelves  ;  and  that  there  must  be  some  force  which  tends 
to  place  the  filings  in  these  lines.  We  notice  also  that  the 
curves  are  closer  together  near  the  poles,  and,  in  fact,  the 
filings  resemble  a  crowd  of  people  massed  around  some 
common  object  of  interest :  the  crowd  is  thickest  around 
the  object,  and  more  scattering  as  the  distance  therefrom 
increases. 

It  appears,  therefore,  that  around  the  pole  of  a  magnet 
exists  this  strange  atmosphere  to  which  we  have  already 
referred,  —  a  so-called  "field  of  force,"  in  which  exist 
strains  and  pulls  and  pushes  as  if  a  host  of  infinitesimal 
beings  were  at  work  seizing  upon  the  filings,  and  arran- 
ging them  to  make  them  accommodate  themselves  to  this 
new  condition  of  affairs.  And  the  result  of  it  all  is,  that 
we  recognize  seeming  lines  of  force  radiating  from  the 
pole.  It  is  a  wonderful  atmosphere,  that  magnetic  field. 
We  have  only  to  move  a  piece  of  iron  in  it,  in  a  peculiar 
way,  to  make  speech  heard  miles  distant,  or  to  produce 
the  light  which  is  weaker  only  than  the  sun  in  power ; 
and  what  still  stranger  things  may  yet  be  done,  no  one 
knows.  Meanwhile  these  lines  of  force,  which  we  see 
mapped  for  us  by  the  iron-filings,  have  some  singular 
properties  of  their  own.  They  never  have  a  free  end. 
The  finding  of  a  free  end  to  a  magnetic  line,  and  of  the 
place  whence  the  rainbow  rises,  and  the  invention  of  a 


76 


THE  AGE   OF  ELECTRICITY. 


magnetic  motor,  are  all  will-o'-the-wisps  together.  Every 
magnetic  line  that  starts  gets  somewhere.  If  apparently 
curving  from  a  north  pole,  it  will  end  in  a  south  pole,  — 
perhaps  the  south  pole  of  the  same  magnet,  perhaps  the 
south  pole  of  some  other  magnet,  and  perhaps  in  a  south 
pole  induced  by  itself  in  a  magnetic  body. 

There  must  be, 
however,  a  magnet  or 
magnetic  body ;  and 
Gilbert,  the  reader 
will  remember,  —  not 
tSih-er C/tit/vv  ^~  Gilbert  who  wrote 
"De  Magnete,"  but 
a  later  Gilbert  who 
wrote  "Pinafore" 
and  ';  Patience,"  — 
has  very  clearly  de- 
monstrated this  in  a 
pathetic  ballad  about 
a  magnet  which  vainly  attempted  to  attract  a  silver  churn. 
That  magnet  sent  out  no  lines  of  force  toward  the  silver 
churn  ;  and  perhaps  it  may  be  well  to  illustrate  this  sad 
condition  of  affairs,  just  to  fix  the  idea  in  our  minds.  No 
lines  of  force  in  Fig.  22  go  to  the  silver  churn  ;  but  if 
the  churn  had  been  of  iron,  the  result,  as  we  see,  would 
have  been  very  different,  and  then 

"  This  magnetic 

Peripatetic 
Lover  who  lived  to  learn, 

By  no  endeavor 

Can  magnet  ever 
Attract  a  silver  churn,"  — 


Iron  C/iur/v 

Fig.  22. 


might  not  have  wasted  his  rejected  fascinations. 


THE  ELECTRO-MAGNET. 


77 


And  this  also,  by  the  way,  indicates  the  reason  why  the 
officers  of  Atlantic  steamers  show  so  much  uneasiness 
when  young  ladies  persist  in  bringing  their  sewing  appara- 
tus into  the  neighborhood  of  the  compasses.  The  lines 
of  force  from  the  north  pole  of  a  very  sedate  and  responsi- 
ble compass-needle  may  find  easily  a  south  pole  in  the 
frivolous  knitting  or  crochet  needle,  and,  turning  in  the 
direction  of  the  latter,  may  lead  the  ship  miles  from  her 
course. 

It  has  been  said  that  a  magnet,  when  it  attracts  a  body 
of  magnetic  material,  first  induces  magnetism  in  the  latter. 
Thus  by  simply  placing  a  piece  of  iron  in  a  magnetic  field, 
and  taking  it  out  again,  we  can  render  that  iron  magnetic 
or  non-magnetic,  as  it  is  termed,  by  induction.  If,  how- 
ever, we  wish  to  render  the  metal  permanently  magnetic, 
we  can  do  so  by  rubbing  it  with  a  permanent  magnet  in  a 
peculiar  way. 

We  have  stated  that  in  two  instances  in  nature  this 
strange  surrounding  atmosphere  is  produced.  We  have 
seen  it  proved  by  the  behav- 
ior of  the  iron-filings  in  the 
neighborhood  of  the  pole  of 
a  magnet.  It  remains  to  de- 
tect it  around  the  conductor 
of  an  electric  current.  This 
is  easily  done.  Take  a  piece 
of  card,  or,  better,  a  sheet  of 
glass,  through  which  a  hole 
has  been  drilled,  and  pass  the 
wire  through  which  the  current 
is  moving,  through  the  hole. 
Then  sprinkle  iron-filings  around  the  wire.  The  filings 
will  arrange  themselves  in  a  series  of  concentric  circles, 
just  as  if  they  were  controlled  by  a  whirlwind,  around  the 


Fig.  23. 


78 


THE  AGE   OF  ELECTRICITY. 


wire.  This  is  beautifully  represented  in  Fig.  23,  which  has 
been  prepared  from  a  photograph.  If  the  wire  is  carried 
parallel  to  and  across  the  glass  plate  as  in  Fig.  24,  the 

filings  will  arrange  them- 
selves in  straight  lines  per- 
pendicular to  the  direction 
of  the  wire  and  at  equal 
distances  from  one  another  ; 
and  may  be  regarded  as  a 
number  of  repetitions  of 
Fig.  23,  strung  upon  a  wire, 
and  looked  at  edgeways. 

This    is    different     from 

F'9'24-  what    happens    with    the 

magnet.      Compare  Figs.  18  and  23. 

If  we  suppose  the  lines  of  force  indicated  by  the  iron- 
filings  to  represent  a  wind 
blowing,  then  a  flag  placed 
near  a  magnet  would  stand 
as    in   Fig.    25;   whereas,      ;,'^ 
if  the  flag  were  placed  near 
the  wire,  it  would  stand   as   in  Fig. 


Fig.  25. 


26.  A  suspended 
magnetized  needle  would  place  it- 
self in  the  same  positions  with  ref- 
erence to  wire  or  magnet,  under  the 
influence  of  the  lines  of  force. 

A  wire  conducting  a  current, 
therefore,  is  surrounded  by  lines  of 
force  like  those  surrounding  the 
natural  magnet,  but  differently  dis- 
posed. Such  a  wire  is,  in  fact,  a 
magnet.  It  will  attract  iron-filings ; 

and  they  will  cling  to  it  as  long  as  the  current  continues, 

but  drop  off  as  soon  as  the  current  stops. 


THE  ELECTRO-MAGNET. 


79 


Now,  suppose  we  wind  our  conducting  wire  into  a  helix 
or  coil,  as  in  Fig.  27.  If  the  entire  length  of  the  wire  is 
surrounded  by  the  whorl  of  lines  of  force,  clearly  a  great 
many  of  these  lines  will  /•. 

converge  in  the  space  in- 
side the  coil,  and  we  shall 
have  there  a  very  strong  or 
concentrated  field  of  force. 
Into  this  field  we  can  easily 
insert  an  iron  bar,  which  will  then  become  very  strongly 
magnetized.  That  is,  just  as  it  would  become  a  magnet 
if  placed  in  the  field  of  another  magnet,  so  now  it 
becomes  a  magnet  when  placed  in  the  field  of  force  of 
the  wire. 

This  is  very  perfectly  illustrated  in  Fig.  28.  Here  the 
wire  is  represented  with  a  turn  in  it,  and  the  lines  are  thus 


Fig.  27. 


Fig.  28. 


Fig.  29. 


perpendicular  to  the  plane  of  the  loop.  The  filings  now 
form  themselves  (as  far  as  the  plate  will  allow  them)  into 
lines  perpendicular  to  the  plane  of  the  paper,  and  there- 
fore, as  seen  from  above,  appear  simply  as  isolated  dots 
or  points.  Fig.  29  illustrates  the  lines  of  force  brought 
into  play  in  the  manner  above  described  in  the  induction 


80  THE  AGE   OF  ELECTRICITY. 

of  magnetism  in  an  iron  bar  when  an  electric  current  is 
sent  through  a  wire  coiled  around  it.  It  represents  a 
small  electro-magnet,  showing  four  turns  of  its  coil.  In 
the  actual  experiment,  the  bar  was  a  strip  of  ferrotype 
iron,  and  the  wire  carrying  the  current  was  threaded 
through  the  eight  holes,  four  being  on  one  side  of  the  bar, 
and  four  on  the  other. 

The  iron  bar  or  core  of  an  electro-magnet,  as  we  have 
said,  temporarily  behaves  like  a  permanent  magnet.  It 
has  a  magnetic  field  of  its  own,  with  endless  lines  of  force, 
and,  in  fact,  is  a  permanent  magnet  —  as  long  as  the 
electrical  current  flows  in  the  coil  surrounding  it.  And 

it  is  worth  while  to 
repeat  this  very  im- 
portant distinction. 
A  permanent  magnet 
is  always  a  magnet : 
an  electro-magnet  is 
not  a  magnet  except 

Fjg  30  when   the    electrical 

current  is   passing 

through  its  coil.  It  i3  a  difficult  thing,  comparatively 
speaking,  either  to  convert  a  piece  of  iron  into  a  per- 
manent magnet,  or  to  render  a  permanent  magnet  free 
from  magnetism.  On  the  other  hand,  an  electro-magnet 
is  energized  or  de-energized  witli  infinite  rapidity,  by 
simply  establishing  or  stopping  the  current  in  the  coil. 
The  poles  of  a  permanent  magnet  are  fixed  :  those  of  an 
electro-magnet  depend  upon  the  direction  of  the  current, 
Thus,  in  Fig.  3-0,  supposing  the  inner  shaded  circle  to  rep- 
resent the  bar,  or  "core"  of  the  magnet,  if  the  current 
moves  in  the  coil  represented  by  the  outer  circle  in  the 
direction  of  the  arrow  in  1,  —  that  is,  in  the  same  direction 
as  the  hands  of  a  watch,  —  the  end  of  the  core  facing  us  is 


THE   ELECTRO-MAGNET. 


81 


JElecti'o  Miufiiet 


Core 


a  south  pole.  If  the  current  travelled  the  other  way>  as  in 
2,  the  same  end  of  the  bar  would  be  a  north  pole.  So 
that  we  can  not  only  make  and  unmake  an  electro-magnet, 
b}^  establishing  or  breaking  the  current ;  but  we  can 
reverse  the  polarity  of  the  magnet  at  will,  by  simply 
reversing  the  direction  of  the  current  in  the  coil. 

In  Fig.  ol  is  represented  in  diagram  an  electro-magnet 
which  communicates  with  a  battery ;  and  a  circuit-closing 
key^  by  manipulating  which  we  can  establish  or  interrupt 
the  current  from  the  battery  through  the  coil  of  the  mag- 
net. In  front  of  the  core  hangs  a  piece  of  magnetic 
metal,  called  the  ar- 
mature; and  this  is 
held  away  from  the 
magnet  by  a  coiled 
spring  fastened  at  its 
opposite  end  to  a 
fixed  post.  In  Fig. 
31,  the  key  is  shown 
raised ;  no  current  ^ 
then  passes  to  the  ^ 
coil,  and  the  bar  is  Fig.  si. 

not  a  magnet. 

If,  however,  we  press  down  the  key,  then  the  current 
from  the  battery  will  instantly  circulate  through  the  coil ; 
the  core  will  become  a  magnet,  and  attract  its  armature  ay 
indicated  by  the  dotted  lines.  If  we  break  the  circuit 
again,  the  armature,  no  longer  attracted,  will  be  drawn 
back  by  the  spring ;  and  hence  we  can  keep  that  armature 
vibrating  to  and  fro  as  often  as  we  can  make  and  break 
the  circuit.  As  the  magnet  may  be  quite  strong,  it  may 
attract  its  armature  with  much  force,  so  that  we  can  make 
the  armature  drive  mechanism.  This  is  how  the  electro- 
magnet converts  electricity  into  mechanical  motion  in  the 


82 


THE  AGE   OF  ELECTRICITY. 


great  majority  of  electrical  devices,  including  the  tele- 
graph, the  electro-motor,  and  the  countless  alarms  and 
kindred  apparatus  to  some  of  which  reference  will  here- 
after be  made. 

There  is  still  another  way  in  which  the  electro-magnet 
can  vibrate  its  armature ;    and  that  is  by  reversing  the 

polarity  of  the  core,  by 
simply  changing  the 
direction  of  flow  of  the 
current.  Suppose,  in 
Fig.  32,  a  current  cir- 
culated around  the  bar 


N 


Jlrniatwe 


Fig.  32. 


or  core,  in  the  direc- 
tion of  the  arrow  ;  then 
the  right-hand  end  would  be  the  north  pole.  If,  instead 
of  suspending  before  our  electro-magnet  an  armature  of 
magnetic  material,  we  suspended  an  armature  itself  a 
magnet,  having  north  and  south  poles,  as  marked  in  the 
diagram,  then,  when  the  nearest  end  of  the  electro-magnet 
became  north,  the  armature  would  be  attracted,  because 
unlike  magnetic  poles  would  be  opposed.  But  if  we 
reversed  the  current,  as 


8 


Fig.  33. 


shown  in  Fig.  33,  then 
like  magnetic  poles  would 
be  opposed,  and  the  arma- 
ture would  be  repelled. 
So  that,  by  simply  making 
the  current  travel  first  in  one  way  and  then  in  the  other, 
we  can  set  a  magnet  or  polarized  armature  into  vibra- 
tion. If  the  armature  were  not  polarized,  of  course  the 
changing  of  the  current  would  have  no  effect  on  it ; 
either  pole  of  a  magnet  attracting  a  simple  magnetic 
body  not  itself  a  magnet.  We  shall  find  this  contriv- 
ance largely  used  in  the  various  practical  applications 


THE  ELECTRO-MAGNET.  83 

of  electricity  ;  although  perhaps  to  not  so  great  an  extent 
as  the  first-mentioned  arrangement,, with  which,  just  as 
the  steam-engine  can  be  controlled  by  throttling  the  steam, 
so  the  magnet  is  controlled  by  throttling  the  current. 

As  we  shall  see  farther  on,  electro-magnets  can  be  made 
to  exert  sufficient  power  to  drive  locomotives,  and  do  other 
heavy  mechanical  work :  so  that  it  is  quite  important  to 
know  something  as  to  how  they  acquire  this.  A  magnet, 
whether  electrical  or  permanent,  has  no  power  of  its  own. 
It  can  only  exert  whatever  energy  is  put  into  it.  It  is 
like  a  clock-spring :  wind  it  up,  and  it  drives  the  clock, 
not  by  some  inherent  clock-driving  capacity  peculiar  to 
springs,  —  like  the  inherent  meat-roasting  quality  ascribed 
by  Martinus  Scriblerus  to  roasting-jacks,  —  but  because 
it  has  been  wound  up.  When  a  body  is  rendered  mag- 
netic, whether  by  electricity,  or  by  natural  means,  or  by 
rubbing,  energy  is  imparted  to  it.  When  the  magnet 
exerts  itself,  it  parts  with  some  of  that  energy.  If  it 
moves  a  heavy  armature  up  to  its  pole,  it  may  expend  all 
the  energy  it  can  exert,  and  will  affect  other  bodies  not 
at  all.  If  a  permanent  magnet  thus  draws  its  armature, 
it  can  do  no  more  until  the  armature  is  withdrawn.  To 
take  away  that  armature,  requires  just  as  much  force  as 
the  magnet  used  in  attracting  it ;  so  that,  by  this  action, 
the  energy  expended  by  the  magnet  in  attracting  ,the 
armature  is  restored  to  it. 

To  the  electro-magnet,  we  impart  power  by  the  current. 
The  stronger  the  current,  the  stronger  the  magnet,  up  to  a 
certain  point.  Eventually,  however,  the  iron  of  the  core  be- 
comes "  saturated,"  that  is,  it  reaches  a  state  when  it  can 
apparently  be  no  longer  affected.  If  the  current  is  kept  con- 
stant, and  the  magnet  below  saturation,  then,  the  greater  the 
number  of  turns  of  wire  applied,  the  stronger  the  magnet. 

An  electro-magnet  is  easily  made  of  a  central  bar  or 


84 


THE  AGE   OF  ELECTRICITY. 


core  of  iron,  around  which  the  insulated  wire  is  coiled  like 
a  spool  of  thread.  Usually  the  core  is  made  in  the  form 
of  a  horse-shoe,  so  that  both  poles  may  be  applied  to  one 
iron  armature.  The  coil  is  then  divided  into  two  parts,  as 
shown  in  Fig.  34.  In  this  engraving  the  magnet  is  rep- 
resented as  having  attracted  its  armature,  —  the  plate 
immediately  beneath  the  coils,  —  and  is  sustaining  weights 


Fig.  34. 

on  a  platform  dependent  therefrom.  An  electro-magnet 
was  designed  by  Professor  Joule,  capable  of  supporting 
in  this  way  over  a  ton,  and  of  exerting  an  attraction  on 
its  armature  of  about  two  hundred  pounds  per  square  inch. 
The  Stevens  Institute  of  Technology  possesses  one  of 
the  largest  electro-magnets  in  the  world.  It  weighs  about 
sixteen  hundred  pounds,  and  has  a  lifting  force  of  nearly 
forty  tons. 


THE  ELECTRO-MAGNET.  85 

It  is  generally  believed  that  the  effect  of  magnetizing 
the  iron  core  is  to  cause  each  particle  of  the  iron  to  try 
to  set  itself  at  right  angles  to  the  direction  of  the  current 
in  the  coil,  just  as  Oersted's  needle  places  itself  at  right 
angles  to  the  wire  conveying  a  current.  The  result  is, 
that  the  irregularly  shaped  particles  place  themselves  with 
their  longer  axes  parallel  to  the  core  ;  and,  as  they  all  do 
this,  the  core  as  a  unit  becomes  longer  and  thinner.  Of 
course  it  is  very  hard  to  realize  how  this  can  happen  in  a 
body  as  dense  and  hard  as  iron ;  and  so  it  is  difficult  to 
imagine  the  vibration  of  the  atoms  when  iron  is  heated,  or 
to  conceive  of  the  infinitesimal  shortness  of  the  paths  over 
which  they  must  move.  Still  it  is  quite  certain  that  this 
is  what  does  occur.  By  actual  measurement  a  rod  of  iron 
magnetized  to  saturation  is  found  to  have  increased  to  the 
extent  of  ^oVon  °f  its  length.  And  even  if  this  change 
is  too  small  for  our  eyes  to  perceive,  it  is  perfectly  easy  to 
hear  it ;  for  the  core  can  be  arranged  not  only  so  that  it 
will  give  out  a  very  perceptible  tick  when  magnetized,  but, 
if  the  current  be  sent  from  a  telephone  transmitter,  it  will 
sing  and  talk,  the  sounds  being  produced  simply  by 
changes  in  the  bar  itself. 

There  is  hardly  a  parallel  instance,  in  the  history  of 
electricity,  of  a  discovery  being  so  rapidly  turned  to  prac- 
tical account  as  was  that  of  Oersted.  He  performed-  his 
successful  experiment  in  causing  the  free  needle  to  be 
moved  by  a  current  traversing  a  wire,  as  we  have  stated, 
in  the  summer  of  1820.  Arago  and  Ampere,  in  France, 
at  once  began  investigations.  By  the  end  of  the  follow- 
ing September,  Arago  announced  that  he  had  ascertained 
that  iron-filings  were  attracted  "by  the  connecting-wire 
of  the  battery,  exactly  as  by  a  magnet,"  and  that  he  had 
magnetized  a  sewing-needle  permanently  by  the  galvanic 
current.  Ampere  reported  almost  immediately,  that  a 


86  THE  AGE  OF  ELECTRICITY. 

spiral  or  helical  arrangement  of  the  galvanic  conducting- 
wire  was  most  advantageous  for  magnetizing  needles. 
Early  in  November,  he  "  perfectly  imitated  a  magnet  by  a 
helical  galvanic  conducting- wire."  Four  years  later,  Wil- 
liam Sturgeon  made  the  electro-magnet,  using  a  core  of 
iron  bent  in  horse-shoe  form,  coated  with  varnish,  and  sur- 
rounded with  a  spiral  coil  of  naked  copper  wire.  Shortly 
afterwards,  Professor  Joseph  Henry  made  his  famous 
experiments  at  the  Albany  Academy,  which  revealed  for 
the  first  time  the  extraordinary  power  of  the  electro-mag- 
net. Henry  followed  the  plan,  previously  suggested  by 
Schweigger,  of  covering  his  wire,  instead  of  merely  putting 
the  insulating  material  around  the  coil  as  Sturgeon  had 
done.  With  a  magnet  wound  with  twenty-six  strands  of 
copper  bell-wire  covered  with  cotton  thread, — the  aggre- 
gate length  of  the  core  being  728  feet  —  he  had  suspended 
nearly  a  ton  weight.  Afterwards,  with  a  small  horse-shoe 
of  round  iron,  one  inch  in  length  and  six-tenths  of  an 
inch  in  diameter,  wound  with  but  three  feet  of  brass  wire, 
he  raised  a  weight  420  times  greater  than  that  of  the  mag- 
net itself.  Sir  Isaac  Newton  describes  a  lodestone  weigh- 
ing three  grains,  which  he  wore  in  a  ring,  and  which  is 
said  to  have  raised  746  grains,  or  250  times  its  own  weight. 
This  is  the  greatest  recorded  strength  of  any  permanent 
magnet.  Natural  magnets,  or  lodestones,  are  stronger 
than  those  artificially  made.  The  former  usually  carry  a 
load  of  about  twenty  times,  while  the  latter  are  rarely  able 
to  lift  a  mass  exceeding  five  times,  their  own  weight. 
Within  recent  years,  however,  very  powerful  permanent 
magnets,  equal  to  the  lifting  of  twenty-five  times  their 
own  weight,  have  been  constructed  by  M.  Jamin  ;  the 
advantage  being  gained  through  the  use  of  very  thin  leaves 
of  thoroughly  magnetized  steel,  bound  together  to  form 
the  magnet. 

Let  us  sum  up  some  of   the  strange  phenomena  thus 


THE  ELECTRO-MAGNET.  87 

far  briefly  outlined.  We  have  seen  that  the  electrical 
current  is  competent  to  produce  effects  not  merely  in  its 
channel  or  conductor,  —  like  water  turning  a  wheel, — 
but  to  influence  bodies  entirely  outside  of  that  channel. 
It  causes,  around  its  conductor,  a  peculiar  aura  or  atmos- 
phere like  that  around  the  poles  of  a  magnet,  but  differing 
from  the  latter  as  a  whirlwind  differs  from  a  steady  gale. 
It  converts  the  conductor  into  a  magnet,  which,  like  other 
magnets,  is  capable  of  influencing  magnetic  bodies  to  be- 
come magnets.  It  also  converts  magnetic  bodies,  around 
which  the  conductor  is  wound,  into  magnets  ;  and  a  bar  of 
iron  in  this  way  is  given  all  the  properties  which  it  would 
have  were  it  normally  and  naturally  a  magnet,  or  piece  of 
lodestone.  This  is  an  electro-magnet.  But  the  magnetic 
state  of  this  bar  is  controllable.  It  is  a  magnet,  or  not, 
in  accordance  as  we  permit  the  current  to  flow,  or  inter- 
rupt it.  As  a  magnet,  the  bar  has  different  poles,  at 
opposite  ends ;  but  these  poles  change  reciprocally  in 
accordance  with  the  direction  of  the  current.  By  making 
and  breaking  the  current,  we  can  make  the  electro-magnet 
attract  and  release  alternately  a  piece  of  magnetic  mate- 
rial, placed  in  front  of  either  of  its  poles,  and  called  an 
armature.  If,  however,  the  armature  be  itself  a  magnet, 
then  we  can  make  the  electro-magnet  attract  or  release  it 
without  breaking  the  current,  but  by  simply  changing  the 
direction  of  the  current,  —  this  because,  when  the  magnet 
opposes  an  unlike  pole  to  the  adjacent  pole  of  the  arma- 
ture, the  latter  will  be  attracted  ;  but  when  the  magnet 
presents  a  like  pole,  the  armature  will  not  be  attracted,  or, 
if  already  attracted,  will  be  released. 

Why  the  magnet,  and  the  conductor  carrying  a  current, 
produce  this  singular  atmosphere  ;  why  other  bodies  act 
as  they  do  in  that  atmosphere  ;  what  the  medium  is  which 
carries  this  unknown  force  between  the  separated  magnet 
and  armature,  —  are  all  unsolved  problems. 


88  THE  AGE  OF  ELECTRICITY. 


CHAPTER  VII. 

THE    DYNAMO-ELECTRIC    MACHINE,    AND    THE    CONVERSION   OF 
MAGNETISM  AND  MECHANICAL  MOTION  INTO  ELECTRICITY. 

Is  electricity  magnetism ?  or  is  magnetism  electricity? 
Are  these  phenomena  two  different  forms  of  energy?  or 
are  they  phases  merely  of  the  same  form?  The  last  is 
probably  true. 

By  means  of  the  electric  current,  a  body  capable  of 
being  magnetized  may  be,  as  we  have  seen,  converted 
into  a  magnet.  We  have  now  to  note  even  more  extraor- 
dinary results  following  the  reverse  of  this  ;  namely,  the 
production  of  electrical  currents  by  magnets. 

In  the  fall  of  1831,  Professor  Faraday  announced  that 
from  a  magnet  he  had  obtained  electricity.  On  the  8th 
of  February,  1832,  he  entered  in  his  note-book:  "This 
evening,  at  Woolwich,  experimented  with  magnet,  and 
for  the  first  time  got  the  magnetic  spark  myself.  Con- 
nected ends  of  a  helix  into  two  general  ends,  and  then 
crossed  the  wires  in  such  a  way  that  a  blow  at  a  b  would 
open  them  a  little.  Then  bringing  a  b  against  the  poles 
of  a  magnet,  the  ends  were  disjoined,  and  bright  sparks 
resulted. ' ' 

Next  day  he  repeated  this  experiment,  and  then,  as  was 
his  habit,  invited  some  of  his  friends  to  see  the  new  light. 
He  had  a  piece  of  soft  iron,  surrounded  by  coils  of  wire 
insulated  with  calico  and  tied  by  common  string.  When 


THE  DYNAMO-ELECTRIC  MACHINE. 


89 


he  touched  the  pole  of  a  magnet  with  the  soft  iron,  the 
ends  of  the  coil,  as  he  says,  opened  a  little,  and  a  spark 
passed  between  them.  An  electrical  current  had  been 
caused  in  the  coil,  and  Herbert  Mayo  described  it  in  the 
following  neat  impromptu  :  — 

"Around  the  magnet,  Faraday 
Was  sure  that  Volta's  lightnings  play; 

But  how  to  draw  them  from  the  wire  ? 
He  drew  a  lesson  from  the  heart : 
"Tis  when  we  meet,  'tis  Vhen  we  part, 
Breaks  forth  the  electric  fire." 


Faraday's  experiment  is  very  easily  repeated  with  the 
aid  of  the  little  apparatus  represented  in  Fig.  35.  The 
operator  holds  in  one 
hand  an  ordinary  horse- 
shoe magnet,  and  in  the 
other  a  bar  of  iron  around 
which  is  wound  a  little 
coil  of  insulated  copper 
wire.  On  one  end  of 
the  coil  is  a  small  disk 
of  copper.  The  other 
end  is  sharpened  to  a 
point,  and  brought  in 
contact  with  the  disk. 
On  placing  the  bar  across 
the  poles  of  the  magnet, 
and  then  suddenly  breaking  contact,  the  point  and  the 
disk  become  separated  at  the  same  time,  and  the  spark 
appears. 

Some  fifty  years  earlier,  one  of  those  intensely  practical 
individuals  who  see  no  outcome  in  the  results  of  scientific 
discovery  unless  the  same  can  be  immediately  estimated 


Fig.  35. 


90  THE  AGE  OF  ELECTRICITY. 

at  a  money  value,  rather  superciliously  asked  Franklin 
what  use  there  was  in  the  facts  proved  by  certain  of  his 
experiments. 

44  What's  the  use  of  a  baby?  "  the  philosopher  retorted. 

Faraday's  reply  to  those  who  saw  nothing  gained  by  the 
development  of  the  little  spark,  and  who  demanded  its 
utility,  was  equally  sententious.  "Endeavor  to  make  it 
useful,"  he  said.  He  left  to  others  the  immediate  work 
of  doing  so.  Some  twenty-five  years  later,  he  saw  that 
tiny  flash  expanded  into  the  magnificent  blaze  of  the 
famous  South  Foreland  light-house.  To-day  it  illuminates 
the  thoroughfares  of  the  great  cities  of  the  civilized 
world. 

The  first  practical  magneto-electric  machine  was  con- 
structed by  M.  Hippolyte  Pixii  of  Paris,  in  September, 
1832.  His  apparatus  consisted  of  an  ordinary  horse-shoe 
magnet,  under  the  poles  of  which  a  powerful  steel  horse- 
shoe was  rotated  by  a  shaft.  On  the  steel  horse-shoe  was 
coiled  a  wire  ;  and  as  the  ends  of  the  horse-shoe  were  moved 
up  to  and  removed  from  the  poles  of  the  magnet,  electric 
currents  were  produced  in  the  coil.  The  best  form  of 
this  apparatus  was  probably  that  produced  by  Clarke 
of  London,  in  1834.  This  is  represented  in  Fig.  36.  It 
embodies  a  large  permanent  magnet  AB,  beside  the  poles 
of  which  are  rotated  two  pieces,  or  cores,  of  soft  iron, 
each  encircled  by  a  coil  of  fine  wire,  and  mounted  at  the 
ends  of  arms  supported  on  a  horizontal  shaft ;  the  shaft 
being  rotated  by  turning  the  large  belt-wheel  by  its  handle. 
When  the  coils  are  rotated  in  front  of  the  magnet,  cur- 
rents are  produced  in  them.  The  coils  are  connected  to 
separate  metal  plates  on  each  side  of  the  shaft,  from 
which  plates  the  current  is  led,  by  springs  touching  them, 
to  binding-posts  to  which  conducting-wires  may  be 
attached. 


THE  DYNAMO-ELECTRIC  MACHINE. 


91 


It  will  be  apparent  that  these  machines  are  merely 
convenient  mechanical  contrivances  for  doing  just  what 
Faraday  did  in  the  little  experiment  first  described  in  this 
chapter.  We  have,  however,  by  no  means  recognized  all 
that  Faraday  then  discovered. 


Fig.  36. 


As  we  have  seen,  he  determined  that  an  electrical  cur- 
rent was  produced  in  a  closed  coil  of  wire  when  a  magnet 
was  brought  up  to  the  coil,  or  the  reverse.  The  coil 
might  be  moved  in  front  of  the  pole  of  the  magnet,  as  in 


92 


THE  AGE   OF  ELECTRICITY. 


Fig.  87. 


Clarke's  machine  above  described  ;  or  the  magnet  may  be 
moved  up  to  or  into  the  coil,  as  represented  in  Fig.  37. 
In  the  latter  case,  the  ends  Jf'  of  the  coil  may  be  connected 
with  a  galvanometer,  which  will 
reveal  the  presence  of  the  current. 
It  must  not  be  understood  that 
the  mere  proximity  of  the  magnet 
to  the  coil  produces  any  current, 
for  that  is  not  the  fact.  It  is  the 
motion  of  the  coil  to  the  magnet, 
or  of  magnet  to  coil,  which  pro- 
duces the  current.  The  actual 
mechanical  work  which  we  per- 
form in  moving  either  coil  or  mag- 
net is  converted  into  the  other 
form  of  energy  which  we  call  elec- 
tricity. But  how  this  is  done,  is  not 
easy  to  realize.  We  have  seen  that  all  around  a  magnet 
exists  the  so-called  field  of  force,  and  that  magnetic 
bodies  become  magnets  on  being  simply  placed  therein. 
Here,  however,  is  a  new  property  of  that  mysterious  at- 
mosphere. If  a  closed  circuit  is  moved  in  that  Held,  a 
current  will  traverse  the  wire  ;  or  if  the  field  itself,  by 
moving  the  magnet, 
be  brought  nearer  to 
or  farther  from  the 
coil,  the  same  thing 
will  happen. 

It  is  necessary, 
however,  that  the 
motion  should  be 

made  in  a  certain  way ;  that  is,  so  that,  by  reason  of  the 
change  of  its  position,  either  more  or  less  of  these  singu- 
lar endless  lines  of  force  which  make  up  the  magnetic 


THE  DYNAMO-ELECTRIC  MACHINE. 


93 


field  shall  pass  through  the  coil.  There  are  various  ways 
of  doing  this.  We  can  move  our  coil  from  a  place  where 
the  lines  of  force  are  very  numerous,  —  as  near  the  pole 
of  a  magnet,  —  to  a  place  where  they  are  not  so  numerous, 
as  indicated  by  the  positions  1  and  2  of  the  ring  in  Fig. 


Fig.  39. 


Fig-  40. 


38,  or  1,  2,  and  3,  in  Fig.  39.  Or,  we  can  turn  the  coil 
on  its  axis,  as  in  Fig.  40  ;  in  which  case,  fewer  lines  of 
force  will  pass  through  it  when  it  lies  horizontal  than  when 
it  stands  upright.  Or,  we  can  move  the  coil  simply  past 
the  pole,  as  in  Fig.  41  ;  the  coil  here  travelling  in  the 


direction  of  the  arrow  successively  into  the  positions  1,  2, 
3,  so  that  it  thus  moves  into  and  out  of  the  field  of  the 
magnet.  If,  however,  the  coil  should  be  so  moved  that 
the  number  of  lines  of  force  passing  through  it  is  not 
changed,  then  no  current  would  be  produced  in  its  con- 
volutions. 


94 


THE  AGE   OF  ELECTRICITY. 


We  can  easily  imagine  lines  of  force  extending  from  the 
pole  B  of  the  magnet  in  Fig.  37  ;  and  hence  it  will  be 
apparent  that  more  or  less  of  these  lines  will  be  cut,  or, 
rather,  that  more  or  less  of  them  will  enter  the  enclosing 
coil,  whether  the  magnet  be  moved  into  or  out  of  the  coil, 
or,  conversely,  whether  the  coil  be  moved  on  and  off  the 
magnet. 

If,  for  the  permanent  magnet  of  Fig.  37,  we  substitute 
an  electro-magnet  as  in  Fig.  42,  the  results  will  be  the 

same.  The  field  of  force  now 
produced  at  the  pole  or  end  of 
the  core  resembles  the  field  of 
force  of  the  natural  magnet ; 
and  the  same  movements  of 
either  coil  or  magnet,  as  de- 
scribed with  reference  to  the 
preceding  figure,  will  cause 
currents  in  the  large  coil. 

Fields  of  force,  however, 
exist  not  merely  around  the 
poles  of  magnets,  but  around 
wires  conveying  currents  ;  and 
the  properties  of  the  atmos- 
pheres, in  either  case,  are  simi- 
lar. If  this  be  true,  then  it 
should  follow,  that  if,  in  Fig.  42,  we  remove  the  magnet 
bar  altogether,  and  retain  simply  the  wire  coil,  the  current 
circulating  in  that  coil  should  produce  around  it  a  field 
of  force  which  should  set  up  a  current  in  another  and 
adjacent  coil.  This  is  the  fact,  and  it  forms  a  later  dis- 
covery by  Faraday. 

In  Fig.  43,  the  small  coil  of  wire  connected  with  the 
battery,  and  hence  conveying  a  current,  is  introduced  into 
and  removed  from  the  large  coil  connected  with  the  gal- 


Fig.  42. 


THE  DYNAMO-ELECTRIC  MACHINE. 


95 


vanometer.  Whenever  this  is  done,  the  galvanometer 
needle  swings,  proving  the  existence  of  a  current  in  the 
larger  coil. 

So  far,  we  have  dealt  with  moving  bodies.  A  magnet, 
permanent  or  electro,  moved  with  reference  to  a  closed 
coil,  produces  in  the  latter  a  current.  The  coil,  moved 
with  reference  to  the  magnet,  accomplishes  a  like  result. 
A  coil  of  wire  in  which  a  current  is  flowing,  moved  with 
reference  to  a  closed  coil  in  which  there  is  no  current, 


Fig.  43. 

causes  a  current  in  the  latter :  conversely,  if  the  closed 
coil  be  moved.  In  all  of  these  cases,  it  is  the  energy  of 
motion,  as  we  have  stated,  which  causes  the  electrical 
current. 

There  is,  however,  one  instance  where  we  can  cause  a 
current  in  the  closed  coil,  from  the  coil  in  which  the  cur- 
rent is  circulating,  without  moving  either  of  the  coils  ;  and 
that  is  simply  by  starting  and  stopping  the  current.  The 
coils  are  placed  in  proximity,  .as  one  within  the  other,  and 
so  fixed.  When  there  is  no  current  in  one  coil,  there  is 


96  THE  AGE  OF  ELECTEICITY. 

of  course  no  atmosphere  of  force  to  enter  the  other.  The 
instant  the  current  is  established,  the  atmosphere  exists. 
It  comes  into  being,  and  affects  the  outer  coil,  for  example, 
the  same  as  if  the  inner  coil  were  moved  into  it.  So,  when 
it  disappears,  the  effect  is  as  if  the  inner  coil  were  moved 
out.  This  is  the  principle  of  the  inductorium,  or  induction 
coil,  which  is  fully  described  in  another  chapter. 

To  recapitulate,  therefore :  If  we  bring  a  closed  coil  of 
wire  into  the  strange  magnetic  atmosphere,  we  shall  cause 
a  current  in  the  coil.  So  when  we  take  it  out.  So  when 
we  move  it  from  a  dense  to  a  thin  part  of  the  atmosphere, 
or  vice  versa.  And  it  makes  no  difference,  in  substance, 
whether  we  bring  the  coil  into  the  atmosphere,  or  move 
the  atmosphere  (by  moving  the  thing  which  it  surrounds) 
into  proximity  to  the  coil,  or  cause  the  atmosphere  sud- 
denly to  come  into  existence  around  the  coil. 

Whatever  happens  is  the  result  either  of  the  coming 
into  or  going  out  of  existence,  or  of  proximity,  of  the 
magnetic  atmosphere,  with  relation  to  the  coil ;  or  of 
changes  in  the  position  of  the  coil  in  that  atmosphere. 
To  speak  .of  the  coil  enclosing  more  or  less  of  the  lines  of 
force,  and  the  current  in  the  coil  attending  the  change,  is 
one  convenient  way  of  realizing  what  occurs.  We  can 
express  the  same  idea  by  saying,  that,  in  order  that  the 
coil  may  have  a  current  in  it,  it  must  cut  the  lines  of  force 
in  its  motion,  —  that  is,  move  across  them.  These  theories 
are,  however,  waning.  The  more  modern  view  is,  that  the 
molecules  of  the  wire  in  the  coil  are  in  a  condition  of 
equilibrium,  liable  to  instant  change  ;  and  this  occurs  the 
moment  the  particles  enter  the  magnetic  atmosphere,  or 
field  of  force,  where  they  become  subject  to  new  strains 
and  stresses,  which  introduce  new  conditions  of  balance. 
In  effecting  the  necessary  molecular  changes,  an  expendi- 
ture of  energy  is  involved,  which  results  in  the  current. 


THE  DYNAMO-ELECTRIC  MACHINE.  97 

This  theory  has  been  very  fully  elaborated  by  Professor 
Sprague. 

Of  course  the  three  theories  are,  after  all,  only  different 
ways  of  saying  the  same  thing.  If  a  coil  moves  from  one 
part  of  the  field  to  the  other,  so  that  more  or  less  lines  of 
force  pass  through  it,  it  must  cut  or  pass  across  lines 
of  force  in  so  moving ;  and  similarly,  if,  in  order  to  have  a 
current  caused  in  it,  it  must  proceed  from  one  part  of  the 
field  to  another,  in  which  the  strains  and  stresses  due  to 
the  lines  of  force  shall  be  different,  it  follows  necessarily 
that  it  must  go  to  a  place  where  different  lines  of  force 
(more  or  less)  exist. 

It  is  not  necessary,  however,  to  proceed  farther  into  the 
realm  of  theory.  For  present  purposes  it  is  sufficient  to 
recognize  that  there  is  a  very  broad  distinction  between 
producing  an  electric  current  in  a  coil  of  wire  by  reason 
of  the  actual  motion  of  the  coil  in  the  magnetic  field,  or 
of  the  field  about  the  coil ;  and  by  reason  of  the  establish- 
ment or  change  of  strength  in  a  magnetic  field  about  a 
stationary  coil.  In  the  one  case,  we  convert  the  energy  of 
mechanical  motion  into  electricity  :  in  the  other,  the  energy 
of  one  current  engenders  another  current. 

With  the  apparatus  wherein  the  character  of  the  current 
is  changed  by  the  induction  of  one  stationary  coil  upon 
another,  we  have  nothing  to  do  in  this  chapter. 

We  have  frequently  referred  to  the  field  of  force  which 
surrounds  the  magnetic  pole,  or  current-conducting  wire, 
as  an  atmosphere.  This  is  a  convenient  way  of  thinking 
of  it ;  but  in  fact  it  is  nothing  material  or  tangible,  as  the 
air,  for  example,  is  which  surrounds  our  earth.  The  same 
effects  are  present,  even  when  the  most  perfect  vacuum 
exists  around  the  magnet ;  so  that  it  is  probable  that  the 
magnetic  action  is  propagated  through  space,  by  move- 
ments or  pressure  in  the  ether  which  is  supposed  to  per- 


98  THE  AGE   OF  ELECTRICITY. 

vade  the  entire  universe,  —  to  exist  between  the  atoms  of 
all  bodies,  however  solid,  as  an  infinitely  thin  though  jelly- 
like  medium. 

One  other  important  fact  remains  to  be  noted,  before 
we  examine  the  construction  of  the  machines  which  pro- 
duce electricity  ;  and  that  is  the  changes  in  the  direction  of 
movement  of  current  in  the  coil.  In  referring  to  the  elec- 
tro-magnet, in  the  preceding  chapter,  we  have  found  that 
the  poles  of  the  magnet  depend  on  the  direction  of  the 
current  traversing  the  wire,  and  that  we  can  reverse  the 
pole  simply  by  reversing  the  direction  of  the  current. 
The  direction  of  the  current  of  a  coil  which  is  moving  in 
a  magnetic  field  depends  upon  whether  the  coil  is  moving 
from  a  place  where  it  encloses  more  lines,  to  a  place  where 
it  encloses  less  lines,  or  the  reverse.  The  current  moves 
in  one  direction  in  one  case,  in  the  opposite  direction  in 
the  other ;  and  we  shall'  presently  see  the  effect  of  this 
reversal  in  practice. 

In  the  upper  part  of  the  Western  Union  Telegraph 
Company's  building  in  New  York,  there  is  a  large  room 
in  which  are  disposed  tier  upon  tier  of  galvanic  cells. 
There  is  no  clatter  and  rush  of  machinery,  no  noise  except 
such  as  rises  from  the  busy  street  without,  or  comes  from 
the  numberless  telegraph-instruments  in  another  part  of 
the  building.  Here  are  generated  the  electrical  currents 
which  are  to  find  their  way  over  thousands  of  miles  of 
wire,  and  carry  the  messages  of  the  great  metropolis 
throughout  the  country. 

Not  far  from  the  telegraph-offices  is  the  establishment 
of  one  of  the  corporations  which  provide  the  electric 
lights  which  now  illuminate  the  city  thoroughfares  ;  and 
here  are  generated  the  currents  which  feed  these  miniature 
suns.  But  now,  instead  of  the  perfect  silence  with  which 


THE  DYNAMO-ELECTRIC  MACHINE.  99 

the  mighty  forces  of  chemical  affinity  do  their  work  in  the 
battery,  there  is  the  thunder  of  great  engines,  the  roar  of 
the  escaping  steam,  and  the  bewildering  whirr  of  the  huge 
dynamos.  The  visitor  is  warned  away  from  the  wires  :  it 
is  death  to  touch  them.  Here  and  there  are  brilliant  flashes 
of  light.  An  odd  odor  is  in  the  air.  But  above  all  there 
is  motion,  —  as  driving,  as  headlong,  as  impetuous,  as 
unremitting,  as  that  of  the  locomotive  in  its  hurried 
course. 

As  we  become  accustomed  to  the  confusion  and  noise, 
we  find  that  the  source  of  power  is  a  steam  boiler,  and 
that  the  steam  drives  a  steam-engine,  no  different  from 
other  steam-engines  except  that  it  is  constructed  to  run 
with  especial  steadiness  and  uniformity.  The  work  of 
this  steam-engine  is  to  turn  the  "dynamo;  "  and  in  and 
by  the  dynamo,  the  electricity  is  produced.  This  is  ob- 
viously very  unlike  the  production  of  the  current  by  a 
battery.  There  are  no  chemicals  here,  no  zinc  consumed. 
The  engine  simply  rotates  the  dynamo  shaft ;  and  in  the 
wires  leading  from  the  machine  the  current  circulates,  and 
goes  to  the  lamps. 

The  idea  will  perhaps  occur  to  us,  that,  inasmuch  as 
here  is  a  machine  which  is  rotated,  and  which  produces 
electricity,  we  perhaps  have  in  the  dynamo  only  some 
more  modern  and  improved  form  of  the  old  frictional  or 
static  machine,  in  which  the  glass  or  sulphur  cylinder  is 
excited  by  rubbing.  This  is  very  wide  of  the  truth.  If 
we  could  see  into  the  dynamo,  —  and  it  is  quite  possible 
to  do  so,  in  some  forms  of  the  apparatus,  —  we  should  at 
once  discover  that  the  thing  revolved  does  not  rub  against 
any  thing,  but  apparently  turns  freely  in  the  air.  We 
should  also  notice  that  the  revolving  object  is  substantially 
a  solid  mass  ;  that  there  is  nothing  moving  inside  of  it. 
On  closer  examination,  we  should  find  it  to  be  a  bundle 


100  THE  AGE   OF  ELECTRICITY. 

of  wires  ;  and  if  we  examined  the  mass  of  metal  which 
surrounds  this  rotating  mass  of  wire,  we  should  find  that 
the  same  was  a  magnet  or  perhaps  several  magnets. 

We  thus  recognize  the  dynamo  as  a  machine  wherein 
coils  of  wire  are  moved  in  a  very  intense  magnetic  field 
produced  by  the  encompassing  magnets  ;  and,  from  what 
has  been  before  explained,  we  know  that  it  is  simply 
requisite  to  dispose  these  coils  so  that  they  will  be  carried 
through  this  field,  embracing  at  times  more  and  at  times  less 
of  the  pervading  lines  of  force,  to  cause  in  them  currents  of 
electricity.  This,  however,  is  exactly  what  is  done  in  the 
old  Clarke  magneto  machine,  represented  in  Fig.  36  ;  so 
that  there  is  no  difference  in  principle  between  the  dynamo 
and  the  magneto-electric  machine  as  an  electrical  generator. 

But  we  shall  further  find,  that  in  lieu  of  the  perma- 
nent magnet,  for  producing  the  field,  the  dynamo  has  an 
electro-magnet ;  and  we  have  seen  that  the  strength  of 
an  electro-magnet  is  not  a  permanent  and  fixed  quantity, 
but,  up  to  the  point  of  so-called  saturation,  depends  upon 
the  strength  of  the  current  in  the  coils  surrounding  its  core. 
In  this  way  we  can  make  immensely  strong  magnets,  and, 
consequently,  immensely  strong  fields  of  force ;  and,  the 
stronger  the  field,  the  more  lines  of  force  there  are  in 
it.  Hence  if  we  rotate  coils  of  wire  through  that  field,  they 
will  cut  large  numbers  of  lines  of  force  ;  and  the  conse- 
quence of  this  is  very  strong  currents  produced  in  the  coils. 
And  thus  it  becomes  possible  to  obtain,  from  dynamo- 
electric  machines,  currents  of  electricity  far  stronger  and 
more  powerful  than  ever  could  be  got  from  magneto- 
electric  machines. 

Let  us  now  analyze  this  mechanical  generator  of  elec- 
tricity a  little  more  closely.  The  two  principal  parts  of 
the  machine  are  the  magnets  which  make  the  field  of  lines 
of  force,  —  or  the  field-magnets,  —  and  the  body  which 


THE  DYNAMO-ELECTRIC  MACHINE. 


101 


r 
Iron 


Fig.  44. 


revolves  in  that  field.  This  body  is  called  the  armature  ; 
and  it  consists  of  a  core  or  mass  of  magnetic  metal,  such 
as  iron,  and  the  coils  wound  thereon.  We  have  already 
seen,  that,  when  an  armature  of  iron  is  placed  before  the 
poles  of  a  magnet, 
the  lines  of  force 
will  apparently  run 
into  the  armature. 
Consequently,  if  we 
place  the  coil  which 
is  to  receive  and  to 
cut  these  lines  of 
force,  on  an  iron 
body,  we  place  it  on 
something  which  will 
apparently  draw  the 
lines  of  force  into  the  coil.  If  we  made  the  support  for  the 
coil  of  wood,  for  example,  then  very  much  fewer  lines  of 
force  would  pass  through  the  coil.  This  difference  will  be 
clear  from  Figs.  44  and  45,  which  show  the  lines  passing  to 

an  iron  armature,  and  the  lines 
unaffected  by  the  wooden  one. 
Now  let  us  see  what  happens 
when  a  coil  —  which,  for  con- 
venience, we  will  represent  by 
a  simple  ring  —  moves  around 
between  two  strong  magnetic 
poles.  In  Fig.  4G,  these  poles  are  represented  at  N  and 
S ;  the  ring  is  supposed  to  assume  the  several  positions 
represented.  We  are  going  to  see  a  paradoxical  state  of 
affairs,  which  will  require  some  thought  —  which  the  reader 
can  avoid,  if  he  chooses,  by  skipping  the  next  page  or  so, 
and  reading  only  the  conclusion  of  the  explanation. 
The  lines  of  force  pass  almost  directly  between  the 


N 


Fig.  46. 


102  THE  AGE   OF  ELECTRICITY. 

poles,  as  represented  by  the  dotted  lines.  Beginning  at 
the  left,  the  ring  at  first  stands  nearly  horizontal,  so 
that  hardly  any  of  the  lines  of  force  thread  through  it. 
As  it  is  carried  upward  and  around,  in  the  direction  of 
the  arrow,  toward  a  vertical  position,  the  number  of  lines  of 
force  passing  through,  however,  increases  ;  and  a  current 
is  set  up  in  the  ring,  in  the  direction  of  the  small  arrows. 
As  it  moves  farther,  it  receives  more  and  more  lines  ; 
and  finally  when  it  reaches  the  central  point,  marked  by 
the  vertical  dotted  line,  the  number  of  lines  passing 
through  reaches  a  maximum.  Then  the  ring  begins  to 
turn  flat-ways  again  ;  the  lines  passing  through  it  now 
commence  to  decrease  in  number,  and  the  current  in  the 
ring  changes  direction.  The  decrease  in  the  lines  goes 
on  until  the  ring  becomes  once  more  horizontal.  Now  the 
ring  enters  the  lower  right-hand  quadrant,  and  begins  to 
thread  more  lines  of  force.  But  here  the  current  does 
not  appear  to  change  direction.  This  is  because  we  have 
reversed  the  ring  itself,  and  the  lines  of  force  are  entering 
the  opposite  side  from  that  hitherto  presented ;  so  that, 
although  we  have  an  increase  in  the  lines  of  force,  the 
current  apparently  continues  in  the  same  direction.  This 
state  of  affairs  goes  on  until  the  ring  passes  the  central 
point,  when  the  lines  of  force  running  through  it  begin  to 
decrease.  This  reverses  the  current  in  the  ring,  which 
after  passing  through  the  left-hand  lower  quadrant  reaches 
its  starting-point. 

It  is  not  particularly  easy  to  understand  this,  chiefly 
because  it  is  necessary  to  bear  in  mind  both  the  reversal 
of  the  current  and  the  reversal  of  the  ring.  The  current 
changes  in  space  on  passing  the  pole  where  the  lines  de- 
crease or  increase,  so  that  there  is  no  variation  from  the 
law.  But  it  does  not  change  with  reference  to  the  ring. 
This  can  be  shown  rather  neatly  in  the  following  way : 


THE  DYNAMO-ELECTRIC  MACHINE.          103 

Let  the  black  circle  of  Fig.  47  represent  the  ring,  with  the 
currents  flowing  in  it  in  the  direction  of  the  arrows,  — 
that  is,  in  the  direction  in  which  the  hands  of  a  watch 
move.  Now  let  the  reader  hold  this  page  up  to  the  light, 
and  look  at  the  figure  from  the  rear  of  the  page.  It  will 
look  like  Fig.  48.  According  to  the 
arrows,  the  current  will  be  moving  op- 
posite the  hands  of  a  watch,  and  in  just 
the  reverse  direction  from  before.  That 
comes  from  simply  reversing  the  ring. 
Suppose,  however,  that  when  we  looked 
at  the  ring  reversed  by  ourselves,  the 
currents  reversed  simultaneously  on 
their  own  account :  then,  instead  of  the  arrows  appearing 
as  in  Fig.  48,  they  would  appear  in  the  reverse  direction  as 
in  Fig.  49.  But  Fig.  49  is  just  the  same  as  Fig.  47  ,•  which, 
as  the  geometry  says,  was  to  be  proved. 

The  sum  and  substance  of  all  this  is,  that,  when  the 
coil  is  carried  around  in  front  of  the  poles,  the  current 
produced  in  it  reverses  in  direction  every  time  it  passes 
the    neutral    line    between    the    poles. 
This  is  what  electricians  call  an  alter- 
nating   current ;    and,  while    it   is   not 
particularly  important  for  the  non-pro- 
fessional reader  to  consider  very  deeply 
why  or  how  it  thus  alternates,  it  is  of 
48.  some   moment   that   the  difference  be- 

tween what  is  meant  by  an  alternating 
current  which  is  constantly  changing  its  direction  like 
a  pendulum,  and  a  continuous  direct  current  which  flows 
but  in  one  way  like  a  river,  be  understood.  From  the 
difference  in  their  capacity  to  produce  either  au  alternat- 
ing or  a  continuous  direct  current,  dynamo  and  magneto 
electric  machines  may  be  divided  into  two  distinct  classes. 


104  THE  AGE   OF  ELECTRICITY. 

Returning  now  to  Fig.  46,  it  will  be  apparent,  that, 
if  we  arrange  a  number  of  coils  around  a  circular  disk, 
and  between  the  poles  of  a  magnet,  we  shall  get  alter- 
nating currents  from  each  coil,  and  thus  a  succession  of 
rapid  alternations  as  the  coils  move  swiftly  past  the  neutral 
points  between  the  poles.  If  we  had  but  a  single  coil, 
then,  in  addition  to  the  current  constantly  changing  direc- 
tion, it  would,  while  flowing,  vary  in  strength.  This  dif- 
ficulty we  overcome,  in  a  measure,  by  multiplying  the  coils 
so  that  each  shall  be  brought  successively  into  operation, 
the  current  beginning  in  one  coil  before  it  has  ceased  in 
another. 

Alternating  currents  are  very  useful  in  many  cases,  but 
for  most  purposes  we  need  a  direct, 
continuous  flow.  We  find  alternating 
action  in  mechanical  devices  very  useful 
in  pumps  and  steam-hammers  ;  but  if  a 
locomotive,  for  example,  could  be  moved 
only  a  little  way  in  one  direction,  and 
then  a  little  way  in  the  other,  it  would 
not  be  of  much  use  to  draw  trains. 
Yet  this  is  how  the  piston  in  the  locomotive-cylinder 
travels  ;  and  the  piston,  in  turn,  moves  the  whole  great 
machine.  But  the  locomotive  does  not  follow  the  to-and- 
fro  movement  of  the  piston  ;  because,  when  that  move- 
ment reaches  the  wheels,  it  is  converted  into  a  uniform 
rotary  movement  by  the  crank,  which  pushes  the  wheel 
above  the  hub,  and  pulls  it  below,  so  that  the  wheel  can 
turn  in  one  direction,  and  the  engine  goes  straight  ahead. 
There  is  a  little  contrivance  connected  with  alternating- 
current  machines,  called  a  commutator,  which  does  for  the 
alternating  current  about  what  the  crank  does  for  the  alter- 
nating steam-pressure.  In  its  simplest  form  this  is  repre- 
sented in  Fig.  50,  and  it  can  be  seen  on  a  small  scale  in 


THE  DYNAMO-ELECTEIC  MACHINE.          105 

the  engraving  of  Clarke's  magneto  machine,  Fig.  36» 
This  consists  of  a  simple  piece  of  brass  or  copper  tube, 
slit  longitudinally  into  two  portions,  and  fixed  upon  the 
axis  of  revolution  of  the  armature  so  as  to  revolve  with 
it ;  the  two  halves  of  the  split  tube  being  fixed  upon  a 
small  cylinder  of  ivory  or  other  insulating  material.  One 
half  of  the  tube  is  attached  to  one  end  of  the  wire  of  the 
coil, —  or,  where  there  are  several  coils,  to  like  ends  of 
the  wires  of  all  the  coils,  —  and  the  other  half  to  the  other 
end  or  ends.  Against  the  split  tube  are  pressed  two 
springs  or  brushes,  A  A. 
Suppose  the  armature 
carrying  the  coil  or  coils 
to  be  rotating  in  the  direc- 
tion indicated  by  the  arrow 
in  the  engraving.  During 
one  half  of  the  revolution 
the  current  will  flow  to- 

Fig.  50. 

ward  the  commutator,  and 

during  the  other  half  the  current  will  flow  from  it ;  be- 
cause, as  we  have  seen,  the  current  reverses  during  each 
revolution  of  the  coil.  Now,  as  each  end  of  the  wire  is 
connected  to  a  separate  part  of  the  commutator,  it  follows 
that  while  the  armature  is  passing  one  part  of  its  revolu- 
tion, —  say,  the  upper  part,  —  the  current  will  flow  to 
the  commutator  plate  which  is  uppermost ;  and  while  the 
armature  is  completing  the  other  part  of  its  revolution, 
the  current  (reversed)  will  flow  from  the  other,  or  lower, 
commutator  plate.  Consequently  each  half  of  the  split 
tube  will,  as  it  passes  over  the  top  of  its  axis,  deliver  to 
the  upper  contact  spring  or  brush  the  current  flowing  into 
it,  while  the  lower  contact  brush  will  always  (apparently) 
be  feeding  the  return  currents  back  to  the  lower  half  of 
the  split  commutator  tube.  So  that,  if  we  connected  our 


106 


THE  AGE   OF  ELECTRICITY. 


circuit  wires  to  the  two  brushes,  or  springs,  we  should 
have  a  continuous  current  flowing  in  the  wire  from  the 
upper  brush  to  the  lower  one. 

In  general  it  may  be  stated,  that,  in  all  apparatus  of  the 
alternating-current  type,  there  are  a  number  of  coils  placed 
on  the  rim  of  a  wheel  which  revolves,  and  is  surrounded 
by  fixed  magnets.  Alternating  currents  —  that  is,  cur- 
rents alternately  in  opposite  directions  —  are  produced  in 
the  coils,  and  are  either  used  as  alternating  currents,  or 


N 


Fig.  51. 


are  converted  into  direct  currents  by  being  passed  through 
a  commutator  before  they  go  to  the  line  wire. 

There  are  two  types  of  direct-current  machines,  known 
after  their  inventors  as  the  Gramme  and  the  Siemens 
forms.  A  simple  diagram  of  the  Gramme  apparatus  is 
given  in  Fig.  51.  The  armature  is  a  ring  of  soft  iron, 
around  which  the  wire  is  wound  in  a  continuous  spiral, 
forming  a  closed  circuit.  It  revolves  between  two  poles 
of  opposite  names,  the  lines  of  force  from  which  termi- 
nate in  the  ring ;  as  shown  in  Fig.  52,  which  represents  a 
section  made  through  Fig.  51  by  a  plane  in  the  line  NS 


THE  DYNAMO-ELECTRIC  MACHINE. 


107 


of  Fig.  51  and  at  right  angles  to  the  plane  of  the  paper. 
As  the  ring  revolves,  these  lines  of  force  are  cut  by  the 


Fig.  52. 

moving  wires,  and  electro-motive  forces  are  generated  in 
the  two  halves  of  the  ring,  in  opposite  directions,  so 
that  they  meet  and  op- 
pose one  another  at  the 
neutral  points  JVP,  as  in 
Fig.  53.  As  long  as  no 
further  connections  are 
made,  no  current  is  gener- 
ated. If,  however,  the/y 
points  NP  are  connected 
by  a  wire  in  circuit,  through 
a  number  of  lamps,  for  ex- 
ample, as  in  Fig.  54,  then 
a  current  will  flow  from 
P  to  N.  In  order  to  col-  fig.  63. 

lect  the  currents  from  the 

ring,   a    special  device,  called   a  collector,  is  employed. 
This   is   usually  made   of   a   cylinder  of   wood   or  other 


108 


THE  AGE  OF  ELECTRICITY. 


insulating  material,  upon  which  are  placed  longitudinally 
a  number  of  insulated  metal  strips.  Each  strip  or  bar  is 
connected  by  a  wire  to  the  part  of  the  spiral  coil  imme- 
diately opposite  to  it,  as  represented  in  Fig.  55.  At  the 
points  PN,  where  the  opposite  electro-motive  forces  diverge 
and  join  again,  two  metal  brushes  rub  against  the  strips  ; 
and  with  these  brushes  the  external  circuit  is  connected. 


Fig.    54. 

The  second  type  of  direct-current  dynamo  emplo}Ts  the 
Siemens  or  drum  armature,  in  which  the  coils  of  wire  are 
wound  lengthways  over  a  drum  or  spindle  ;  the  wire  being 
carried  along  the  drum  parallel  to  its  axis,  across  the  end, 
back  along  the  drum  on  the  side  opposite,  and  so  around 
to  the  starting-point ;  the  separate  turns,  or  groups  of 
turns,  being  spaced  out  at  regular  intervals  all  around  the 


THE  DYNAMO-ELECTRIC  MACHINE. 


109 


Fig.  55. 


drum.     This  method  of  winding  is  illustrated  in  Fig.  56. 
In  each  of  the  wires,  as  it  rises  past  the  south  pole,  cur- 
rents are  generated  which  flow  towards  the  front ;   whilst 
in   the   other  half   of 
their     revolution,      in 
descending    past    the 
north    pole,    the    cur- 
rents    generated     in 
them    flow    from     the 
front  towards  _  /y 
the  back.     The 
method  of  joining  the 
coils  to  the  commuta- 
tor bars   insures   that 
the  currents  shall  fol- 
low one  another,  and 
flow    into    the    upper 
contact  brush. 

We  have  now  recognized  the  two  principal  types  of 
mechanical  electrical  generators,  —  namely,  the  alternat- 
ing-current apparatus  and  the  direct-current  apparatus  ; 
the  difference  being  in  the  construction  of  the  armature. 

The  magnets  may 
be  either  perma- 
nent or  electro,  so 
that  the  classifi- 
cation applies  to 
either  magneto  or 
dynamo     electric 

~    ~ *x  machines ;  but  in 

fact     all    so    far 

described  was   invented    some   years  before  the  modern 
dynamo  may  be  said  to  have  begun  its  existence. 

The  Siemens  armature  was  devised  by  Dr.  C.  W.  Sie- 


110  THE  AGE   OF  ELECTRICITY. 

mens,  in  1856  ;  and  the  continuous-ring  armature  was  con- 
trived by  Dr.  Pacinotti  of  Florence,  Italy,  in  1860.  The 
compound  multipolar  armature  dates  back  farther  than 
either. 

In  1867  Mr.  H.  Wilde  replaced  the  permanent  field-mag- 
nets by  electro-magnets  ;  and  these  he  excited  by  means 
of  a  small  separate  magneto  electric  machine  having 
itself  permanent  steel  magnets.  This  was  a  very  ma- 
terial improvement ;  because  the  small  magneto  machine 
utilized  all  its  current  in  exciting  the  electro-magnets  of 
the  larger  apparatus,  which  thus  were  enabled  to  produce 
a  very  intense  field  of  force.  Following  this  came  the 
quadruple  yet  independent  discoveries  of  Hjorth,  Varley, 
Siemens,  and  Wheatstone,  that  there  was  no  need  of  a 
separate  exciting  machine,  for  the  generator  could  be 
made  to  excite  itself.  This  is  somewhat  paradoxical  at 
first,  but  in  reality  not  at  all  difficult  to  understand.  It 
is  necessary,  to  begin  with,  that  the  field  magnets  should 
have  some  little  magnetism  of  their  own.  A  very  little  is 
quite  sufficient.  If  they  are  magnetic  at  all,  they  have 
a  field  of  force  ;  and  in  the  coils  of  an  armature  rotating 
in  that  field,  there  is  therefore  produced  a  very  weak 
current. 

Now  suppose  that  the  wire  which  constitutes  the  arma- 
ture coil  forms  also  the  enveloping  coil  of  the  field-mag- 
nets :  then  the  current  produced  on  the  armature  will 
circulate  around  the  field  -  magnets,  and  increase  their 
magnetism.  Then,  of  course,  their  field  of  force  will 
become  stronger,  and  so  will  the  current  in  the  arma- 
ture ;  and  in  this  way  the  cycle  will  be  completed.  The 
result  is,  that,  in  a  few  seconds  after  the  armature  is 
set  rotating,  the  field-magnets  are  magnetized  to  satura- 
tion,—  or  to  as  great  a  degree  as  they  are  capable  of 
reaching.  This  is  called  the  dynamo  electric  machine ; 


THE  DYNAMO-ELECTRIC  MACHINE. 


Ill 


in  centra-distinction  to  the  apparatus  already  described, 
wherein  the  magnets  are  permanent,  or  always  of  the 
same  strength. 

When  the  dynamo  is  intended  to  produce  alternating 
currents,  the  separate-excitation  system  is  employed.  This 
is  illustrated  in  Fig.  57.  A  small  separate  magneto  ma- 
chine, not  shown,  energizes  the  large  field-magnets  S  N 
by  circulating  in  the  coil  surrounding  the  same,  as  shown 


Fig.  57. 


Fig.  58. 


by  the  arrows.  The  current  produced  by  the  dynamo, 
whose  magnets  are  thus  excited,  moves  in  a  separate 
circuit,  as  shown. 

Fig.  58  represents-  a  self-exciting  dynamo,  on  what  is 
termed  the  series  system.  Here  the  current,  taken  at  one 
of  the  brushes  of  the  commutator,  passes  around  the  field- 
magnets,  and  then  through  the  main  circuit,  and  so  back 
to  the  other  brush. 

Fig.  59  represents  a  self-exciting  dynamo  on  the  so- 


112 


THE  AGE  OF  ELECTRICITY. 


called  shunt  system.  In  this  arrangement,  the  current 
is  divided  ;  part  going  from  the  brushes  around  the  mag- 
nets by  way  of  the  thin  line  of  wire,  and  part  going  by 
the  main  line  to  the  external  circuit. 

Various  other  arrangements  of  the  circuit  wires  for  ex- 
citing the  field-magnets  in  dynamos  have  been  invented. 
The  foregoing  are,  however,  the  most  important. 

Inasmuch  as    the    currents    pro- 
duced by  a  dynamo-electric  gener- 

L|  _____ ator  depend    upon    the  cutting   of 

tj  »  |  \  the  lines  of    the  field  of   force  by 

the  armature,  it  follows  that  it  is 
necessary,  in  order  to  obtain  pow- 
erful currents,  to  cause  the  arma- 
ture coils  to  cut  as  many  of  these 
lines  as  possible  in  the  shortest 
time.  To  this  end,  the  armature  is 
made  to  rotate  very  rapidly,  and 
is  given  a  large  number  of  turns 
of  wire,  or  coils  enclosing  as  much 
area  as  possible.  In  order  that  the 
current  may  not  be  wasted  in  over- 
coming the  resistance  of  the  arma- 
ture coils,  these  are  made  to  offer  as  little  resistance  as 
possible  ;  and,  finally,  as  the  number  of  lines  of  force 
to  be  cut  depends  on  the  strength  of  the  field  of  force, 
the  field-magnets  are  placed  to  concentrate  the  lines  of 
force  as  much  as  possible  across  the  space  where  the 
armature  revolves. 

There  is  an  immense  variety  of  forms  of  dynamo  and 
magneto  electric  apparatus  ;  and  to  review  them,  even  in 
the  briefest  manner,  would  far  exceed  our  present  limits. 
Only  a  few  typical  machines  are  therefore  given. 

Fig.   GO  represents    the    De  Meritens    magneto-electric 


Fig.  59. 


THE  DYNAMO-ELECTRIC  MACHINE. 


113 


machine.  This  contains  one  or  more  rings  carrying  coils 
which  revolve  between  the  poles  of  powerful  steel  magnets. 
As  the  wheel  revolves,  the  polarities  of  the  cores  are  con- 
stantly reversed,  and  currents  are  therefore  induced  on 


Fig.  60. 

the  wires.  The  ring  is  of  light  brass,  and  the  coils  are 
wound  upon  iron  cores.  This  is  an  example  of  an  alter- 
nating-current magneto  machine. 

An   alternating-current   dynamo   is  represented  in  the 


114 


THE  AGE  OF  ELECTRICITY. 


Siemens  machine  shown  in  Fig.  61.  This  consists  of 
two  fixed  iron  rings  carrying  electro-magnets,  which  are 
excited  by  a  small  auxiliary  direct-current  machine.  The 
polarity  of  the  magnets  in  each  ring  is  alternately  north 
and  south,  and  the  polarity  of  each  is  opposite  to  that  of 


Fig.  61. 


the  magnet  facing  it  on  the  other  ring.  Each  magnet  has 
an  extended  flat  pole  plate,  as  shown.  Between  the  two 
rings  of  magnets,  revolves  a  wheel  partly  of  wood,  partly 
of  metal,  carrying  in  its  circumference  a  number  of  coils 
equal  to  the  number  of  magnets  in  each  ring.  As  the 
wheel  revolves,  currents  are  induced  in  these  coils  in  the 


THE  DYNAMO-ELECTRIC  MACHINE. 


115 


manner  already  explained.     The  currents  are  taken  off  by 
springs. 

The  Brush  machine  belongs  to  the  same  general  class 
as  the  foregoing,  but  differs  in  the  construction  of  its 
armature,  which  consists  of  a  wrought-irou  ring,  around 
which  the  wire  is  wound  in  the  hollow  channels,  as  shown 
in  Figs.  62  and  63.  The  ring  revolves  between  magnets 
having  extended  pole  pieces,  the  two  opposed  poles  at  the 
same  side  of  the  ring  being  of  the  same  name. 

The  Siemens  machine  represented  in  Fig.  64  has  an 
armature  in  the  form  of  an 
iron  cylinder,  around  which 
the  wire  is  wound  longitu- 
dinally so  that  the  wire  is 
parallel  to  the  axis.  The 
collector  consists  of  a  num- 


Fig.  62. 


Fig.  63. 


ber  of  strips  of  metal  fixed  on  an  insulating  barrel.  The 
magnets  are  bars  of  wrought  iron,  straight  at  the  ends  and 
curved  in  the  middle.  The  current  in  the  magnetizing-coils 
has  such  directions  that  the  whole  of  the  curved  portion  of 
the  magnets  at  the  top  of  the  machine  has  one  polarity, 
and  that  at  the  bottom  of  the  machine  the  opposite.  The 
outer  ends  of  the  upper  and  lower  magnets,  which  are  of 
opposite  polarities,  are  connected  by  yoke  plates  in  the 
usual  way. 


116 


THE  AGE  OF  ELECTRICITY. 


Fig.  65  represents  a  large  Edison  machine.  The  arma- 
ture consists  of  a  number  of  disks  of  thin  iron  plate,  sep- 
arated by  paper,  and  grouped  together  to  form  a  barrel 
about  three  feet  six  inches  in  length.  A  number  of  cop- 
per bars  are  laid  on  the  circumference  of  this  barrel,  par- 
allel to  the  axis.  The  diameter  of  the  barrel  outside  the 
bars  is  twenty-eight  and  a  half  inches.  The  bars  are  con- 
nected so  as  to  form  a  continuous  circuit,  analogous  to 


Fig.  64. 

the  longitudinally  wound  wire  in  the  Siemens  machine. 
The  whole  armature  revolves  between  the  poles  of  a  very 
large  electro-magnet ;  these  poles  being  immense  blocks 
of  cast  iron,  which  nearly  meet,  but  are  kept  apart  by  the 
brass  distance  pieces  seen  in  the  front  of  Fig.  65.  The 
lines  of  force  from  the  magnets  terminate  in  the  central 
iron  barrel.  The  magnet  coils  are  twelve  in  number,  and 
are  each  eight  feet  long.  This  machine  will  maintain 
from  a  thousand  to  twelve  hundred  lamps  of  sixteen- 


Fig.  65. 


THE  DYNAMO-ELECTRIC  MACHINE.          117 

candle  power  each.  Its  total  weight  is  about  twenty-five 
tons. 

The  foregoing  examples  will  suffice  to  give  a  general 
idea  of  how  dynamos  are  constructed.  Of  the  two  prin- 
cipal types,  those  which  give  the  direct  current  are  the 
best  for  general  use.  For  electro-plating  and  other  electro- 
lytic operations,  a  direct  current  is,  in  fact,  essential ;  and 
it  is  necessary,  of  course,  to  maintain  the  continuous  mag- 
netization of  electro-magnets. 

Alternating-current  machines  are  simpler  in  construc- 
tion ;  and  their  current,  as  will  be  seen  hereafter,  is  espe- 
cially adapted  to  incandescent  lamps.  They  cannot  excite 
their  own  magnets,  nor  can  they  drive  existing  electro- 
motors. Good  dynamo  machines  will  return  from  seventy 
to  eighty  per  cent  of  the  power  expended  in  driving  them, 
in  the  form  of  electricity.  This,  however,  refers  to  large 
machines  :  small  apparatus,  intended  to  be  driven  by  hand, 
cannot  be  depended  upon  to  utilize  much  over  one-fifth  of 
the  power  ;  and,  in  fact,  it  is  better  not  to  use  the  dynamo 
on  a  small  scale,  but  in  such  case  to  substitute  permanent 
magnets  for  the  electro-magnets.  One  of  the  best  forms 
of  machines  of  this  class  contains  a  Gramme  ring  arma- 
ture, revolving  between  cast-iron  pole  pieces  fitted  with  a 
form  of  magnet  devised  by  M.  Jamin.  The  Jamin  mag- 
nets are  exceedingly  powerful,  and  are  made  of  successive 
layers  of  hoop-steel  let  into  and  riveted  to  the  pole  pieces. 


118  THE  AGE  OF  ELECTRICITY. 


CHAPTER  VIII. 

THE     ELECTRIC     LIGHT.  THE     CONVERSION     OF     ELECTRICAL 

ENERGY    INTO    HEAT    AND    LIGHT. 

WHEN  a  current  of  electricity  flows  along  a  wire,  it  is 
opposed  by  the  resistance  of  the  wire  ;  just,  for  example, 
as  a  current  of  water  is  retarded  by  its  friction  against 
the  pipe  which  encloses  it.  Every  one  knows  that  when 
a  body  is  rubbed  against  another  body,  friction  results. 
When  there  is  friction,  there  is  heat ;  and  when  there  is 
much  friction,  the  heat  may  become  intense  enough  to  set 
either  or  both  bodies  on  fire  if  they  are  of  inflammable 
material,  or,  if  not  inflammable,  to  cause  them  to  glow  or 
become  red  or  white  hot.  The  ordinary  friction-match  is 
an  example  of  an  inflammable  body  thus  set  on  fire.  The 
line  attached  to  a  whaler's  harpoon,  after  the  whale  is 
struck,  is  dragged  over  the  side  of  the  boat  so  rapidly 
that  water  must  be  poured  on  it  to  keep  the  wood  rubbed 
from  being  set  on  fire.  The  brake-shoes  of  a  railway- 
car,  rubbing  against  the  wheels  when  the  brakes  are  put 
down,  cause,  by  their  friction,  brilliant  streams  of  intensely 
heated  minute  particles  of  iron.  The  journals  of  these 
wheels,  or  of  any  machinery,  become  highly  heated  by 
the  rubbing  friction  when  no  lubricant  is  present.  A 
piece  of  iron  pounded  smartly  with  a  hammer  becomes 
hot.  The  striking  of  a  bullet  or  cannon-ball  upon  a  mass 
of  iron  is  attended  by  intense  heat  produced  at  the  place 


THE  ELECTRIC  LIGHT.  119 

of  impact,  and  a  bright  flash  of  light.  We  apply  friction 
to  members  of  the  body  benumbed  by  cold,  —  rubbing 
our  hands  together  to  warm  them. 

Of  course  it  should  not  be  understood  that  there  is 
really  mechanical  friction  between  a  current  of  electricity, 
and  the  wire  through  which  it  passes.  As  has  already 
been  explained,  we  speak  of  electricity  as  a  thing,  or 
corporeal  substance,  merely  for  convenience'  sake  in  talk- 
ing about  it.  Its  effect,  however,  in  traversing  a  con- 
ductor, resembles  that  which  might  follow  the  movement 
of  a  body  through  that  conductor,  despite  the  apparent 
solidity  of  the  latter,  in  that  the  conductor  becomes  the 
more  heated  as  it  offers  more  resistance  to  the  flow. 
Consequently,  the  more  resistance  there  is,  the  more  of 
the  energy  of  the  current  is  expended  in  overcoming  it ; 
the  more  work  is  done  at  the  place  where  it  is  overcome. 
Just  as  the  energy  of  the  movement  of  the  hand  which 
strikes  a  friction-match  is  converted  into  the  heat  which 
raises  the  inflammable  material  to  a  condition  when  it 
bursts  into  flame,  so  the  energy  of  the  seemingly  moving 
current  in  overcoming  the  obstacle  offered  by  the  wire 
raises  the  temperature  of  the  wire.  If  the  wire  is  long 
or  thick,  this  elevation  of  temperature  may  be  so  much 
distributed  as  not  to  be  noticeable  ;  but  if  we  make  the 
wire  very  thin,  the  heat  produced  may  be  sufficient  to 
cause  it  to  become  red  hot  or  white  hot  and  so  dazzlingly 
bright,  or,  if  the  wire  is  not  of  a  refractory  material,  to 
melt  it.  If,  to  illustrate,  we  connect  the  poles  of  a  power- 
ful galvanic  battery  with  a  short  piece  of  fine  platinum 
wire,  — platinum  because  it  will  withstand  a  high  tempera- 
ture, —  we  shall  see  the  platinum  become  intensely  hot 
and  glow.  This  is  because  the  energy  of  the  current, 
opposed  by  the  resistance  of  the  very  narrow  path  through 
which  it  is  driven,  heats  its  channel. 


120  THE  AGE   OF  ELECTRICITY. 

As  a  fine  red-hot  wire  will  burn  its  way  easily  through 
many  substances,  instruments  containing  such  wires  are 
used  in  surgery  for  the  performance  of  operations  in 
which  the  cautery  of  the  wire  attending  its  cutting  action 
is  desirable  ;  and  there  have  been  devices  proposed  for 
cutting  timber  and  shearing  sheep  in  the  same  way.  In 
these  cases,  the  heat  of  the  wire  is  utilized. 

When  the  heat  of  a  body  of  metal  is  greatly  augmented, 
it  becomes  intensely  luminous,  —  so  much  so,  that  it  is 
impossible  to  gaze  upon  molten  steel  in  the  furnace  with- 
out the  aid  of  some  means  for  protecting  the  eyes.  The 
sun  itself  is  in  this  intensely  heated  and  luminous  state. 
If  we  use  a  resisting  body  which  will  not  melt,  we  can 
raise  its  temperature  so  high  by  a  strong  electric  current 
that  it  will  glow  with  a  brilliancy  which  is  exceeded  only 
by  that  of  the  sun ;  and  the  luminosity  so  caused  is 
termed  the  electric  light. 

The  electric  light,  therefore,  is  the  direct  application  of 
the  heat  produced  by  the  energy  of  the  electric  current. 
This  energy  is  caused  to  overcome  the  resistance,  usually, 
of  a  short  interval  of  highly  resisting  material,  —  short 
because  it  is  advantageous  to  concentrate  the  heat,  and  so 
have  its  utmost  intensity  in  the  smallest  possible  space. 

The  electric  light  is  not  produced  from  electricity. 
This  sounds  paradoxical,  but  only  so  because  of  our  false 
thinking  again  of  the  current  as  a  tangible  thing.  If  we 
start  with  a  certain  quantity  of  electricity,  —  such,  for 
example,  as  is  generated  by  the  consumption  of  a  given 
amount  of  zinc  in  a  battery,  — that  same  quantity  will  go 
through  its  conductor,  and  may  be,  so  to  speak,  gathered, 
wholly  regardless  of  whether  it  heats  the  conductor  or 
not.  It  makes  no  difference  whether  it  goes  straight  from 
the  cell  to  an  electro-plater's  bath,  where  it  may  cause  the 
deposition  of  a  certain  amount  of  copper ;  or  whether, 


THE  ELECTRIC  LIGHT.  121 

on  its  way  thither,  it  heats  an  electric  lamp :  only  it  will 
take  longer  to  go  through  the  circuit  in  the  last  case.  If 
we  clammed  a  certain  amount  of  water  in  a  mill-pond, 
with  which  to  drive  a  water-wheel,  we  know  perfectly  well 
that  all  the  water  will  go  through  or  over  the  wheel  which 
is  driven  by  it.  The  wheel  simply  takes  the  energy  of 
the  water.  It  does  not  consume  the  water  itself.  So  in 
the  steam-engine.  We  heat  water  to  make  steam.  We 
use  the  energy  thus  imparted  to  it ;  and  after  we  are  done 
with  the  steam,  it  condenses  back  to  water  again.  Of 
course  it  all  ciphers  down  to  the  fundamental  law  that  the 
matter  and  force  in  the  universe  are  alike  indestructible, 
and  that  we  can  merely  change  them  from  one  form  to 
another,  without  addition  to  or  subtraction  from  the  total 
amount.  This,  however,  is  the  deep  water  of  science  ; 
and  this  chapter  is  about  the  electric  light,  and  not  the 
abstractions  of  philosophy. 

Whenever,  then,  an  electric  current  meets  resistance  in 
its  passage,  heat  is  developed.  If  a  body  intensely 
charged  with  electricity  approaches  a  non-electrified  body, 
then  the  current  tends  to  pass  from  the  former  to  the 
latter.  If  the  energy  of  the  current  can  overcome  the 
resisting  medium  between  the  bodies,  it  will  do  so" ;  and 
in  doing  so,  it  will  develop  heat.  Now,  air  is  a  substance 
which  offers  the  highest  resistance  to  the  current.  Hence, 
as  we  have  seen,  it  requires  electricity  of  enormous  electro- 
motive force  to  pass  over  a  very  small  air  interval.  Thus 
a  cloud  may  become  electrified  very  intensely ;  and'when 
it  approaches  a  cloud  oppositely  electrified,  or  of  lower 
potential,  then  the  current  will  force  its  way  through  the 
intervening  air.  In  overcoming  that  resistance,  its  energy 
will  be  converted  into  heat  and  light.  The  flash  thus 
caused  we  call  lightning ;  and  so  the  electric  light  existed 
from  the  beginning.  But  think  of  the  fate  which  would 


122  THE  AGE  OF  ELECTRICITY. 

have  awaited  the  impious  Roman  or  Greek,  a  couple  of 
thousand  years  ago,  who  should  venture  the  prediction 
that  the  streets  of  Rome  or  Athens  would  one  day  be  lit 
by  Jupiter's  thunderbolts,  quietly  blazing  on  the  tops  of 
long  poles  ! 

The  first  electric  light  produced  by  human  agency  was 
obtained  by  Burgomaster  Von  Guericke,  from  his  revolv- 
ing sulphur  globe.  Priestley  says  that  Robert  Boyle  got 
"  a  glimpse  of  the  electric  light  "  before  Von  Guericke  ; 


Fig.  66. 

"for  he  found  that  a  curious  diamond  which  Mr.  Clayton 
brought  from  Italy,  gave  light  in  the  dark  when  it  was 
rubbed  against  any  kind  of  stuff ;  and  he  found  that  by 
the  same  treatment  it  became  electrical." 

In  Gravesande's  "Mathematical  Elements  of  Natural 
Philosophy"  (1731),  appear  the  engravings  Figs.  66  and 
67,  which  are  reproduced  from  that  work  in  facsimile. 
These  represent  the  earliest  methods  of  production  of  the 
electric  light,  other  than  by  the  simple  rubbing  of  amber 
and  like  substances  by  hand.  In  Fig.  66  is  shown  a  glass 
globe  which  is  to  be  "  briskly  whirl'd  in  a  dark  place,  the 
Hand  all  the  while  being  held  against  it,  to  give  it  Attri- 


THE  ELECTRIC  LIGHT. 


123 


tion.  If  the  Globe  be  exhausted  of  its  Air,  it  will  appear 
all  luminous  within,  but  mostly  so  where  the  Hand  touches 
the  Glass.  But  if  the  Globe  has  Air  in  it  and  being 
whirl' d  in  the  same  Manner,  the  Hand  be  applied  to  it, 
no  Light  appears,  either  in  the  inner  or  outer  surface  of 
the  Glass  ;  but  Bodies  at  a 
small  distance  from  the  Glass 
(as  for  Example  at  a  Quar- 
ter of  an  Inch,  or  nearer)  be- 
come luminous  ;  and  so  only 
those  Farts  of  the  Hand  held 
against  the  Glass,  which 
terminate  or  rather  environ 
the  Parts  that  immediately 
touch  the  Globe,  are  lumi- 
nous." 

Observe  the  reason  :  u  that 
Glass  contains  in  it  and  has 
about  its  surface  a  certain 
Atmosphere  which  is  excited 
by  Friction  and  put  into  Vi- 
bratory Motion :  the  Fire 
contained  in  the  Glass  is 
expelled  by  the  Action  of 
this  Atmosphere, ' '  and  ' '  this 
Atmosphere  and  Fire  is  more 
easily  moved  in  a  Place  void 
of  Air." 

Farther  on,  the  author  concludes  that  quicksilver  con- 
tains fire  ;  "for  if  mercury  well  cleaned  be  shak'd  about 
in  an  exhausted  Glass  it  will  appear  luminous  ;  "  and  then 
he  suggests  the  apparatus  represented  in  Fig.  G7,  which  is 
a  bell-glass  from  which  air  has  been  exhausted,  and  into 
which  mercury  is  caused  to  spout  by  the  pressure  of  the 


Fig.  67. 


124  THE  AGE  OF  ELECTRICITY. 

external  atmosphere.  "  The  experiment  must  be  made  in 
a  dark  place,  and  the  mercury  will  appear  luminous." 

These  experiments  were  devised  by  Hawksbee  in  1709. 
He  called  the  mercury  jet  the  "mercurial  phosphorus," 
and  did  not  consider  the  glass  as  in  any  way  concerned 
in  producing  the  light.  "The  greatest  electric  light  Mr. 
Hawkesbee  produced,"  says  Priestley,  "was  when  he 
enclosed  one  exhausted  cylinder  within  another  not  ex- 
hausted, and  excited  the  outermost  of  them,  putting  them 
both  in  motion.  Whether  their  motions  conspired  or  not, 
he  observed,  made  no  difference.  When  the  outer  cylin- 
der only  was  in  motion,  he  says,  the  light  was  very  con- 
siderable, and  spread  itself  over  the  surface  of  the  inner 
glass.  What  surprised  him  most  was,  that  after  both 
glasses  had  been  in  motion  some  time,  during  which  the 
hand  had  been  applied  to  the  surface  of  the  outer  glass, 
the  motion  of  both  ceasing,  and  no  light  at  all  appearing ; 
if  he  did  but  bring  his  hand  again  near  the  surface  of  the 
outer  glass,  there  would  be  flashes  of  light,  like  lightning, 
produced  on  the  inner  glass  :  as  if,  he  says,  the  effluvia 
from  the  outer  glass  had  been  pushed  with  more  force 
upon  it  by  means  of  the  approaching  hand." 

For  a  long  time  after  Hawkesbee,  no  further  experi- 
ments on  the  electric  light  were  made.  In  fact,  the  use 
of  the  rotating  globe  machine  was  discontinued  ;  and  to 
this  circumstance  Priestley  ascribes  the  slow  progress 
afterwards  made  in  electrical  discoveries.  Meanwhile  the 
idea  that  the  electric  spark  could  be  utilized  as  a  light 
did  not  seem  to  strike  any  one.  The  philosophers  kept 
getting  shocks  from  different  things,  and  discovering  after- 
wards that  they  were  electrical.  They  obtained  fine  flashes 
from  cats,  and  pondered  long  over  the  problem  of  why 
cats  gave  sparks;  until  one  Waitz,  having  procured  "a 
dry  dog,"  applied  vehement  friction  to  the  unhappy  aui- 


THE  ELECTRIC  LIGHT.  125 

mal,  and  so  found,  not  only  that  dogs  gave  sparks  as  well 
as  cats,  but  that  these  sparks  were  electrical.  "This," 
remarks  Priestley  in  his  most  owlish  manner,  "  had  been 
supposed,  but  was  not  accurately  ascertained  before." 
One  is  tempted  to  ask  why  ;  but  Priestley  vouchsafes  no 
further  information. 

It  will  be  remembered,  that  in  describing  the  extraor- 
dinary effects  of  the  shock  of  the  Leyden-jar  upon  the 
electricians  of  the  period,  when  it  was  first  produced,  we 
adverted  to  the  exaggerations  of  these  learned  persons. 
It  is  difficult  to  trace  the  history  of  electricity  without 
experiencing  a  sense  of  mild  wonder  as  to  whether  there 
is  not,  perhaps,  some  subtle  influence  of  the  mysterious 
current  exerted  upon  the  moral  faculties  of  those  who 
deal  with  it, — or,  rather,  invent  around  it, — which  in- 
duces them  to  view  facts  differently  from  most  people. 
And  it  is  singular  how  this  peculiar  obliquity  of  vision 
affects  those  who  have  to  do  with  the  electric  light ;  not 
in  these  times  (ns  every  one  who  precipitately  sold  his  gas 
stock  during  the  electric-light  scare  of  1879-80  can  tes- 
tify), but,  of  course,  a  hundred  years  ago. 

There  was  Boze  of  Wittenberg,  who  some  time  before 
had  wanted  to  die  from  the  effects  of  a  shock  for  the  sake 
of  personal  advertisement ;  and  who  had  discovered,  by 
the  way,  that  water  running  from  a  vessel  in  drops  would 
escape  in  a  constant  stream  when  electrified,  a  valuable 
idea  long  afterwards  utilized  by  Sir  William  Thomson 
in  his  siphon  recorder.  Boze  was  a  most  meritorious  in- 
vestigator, until  he  became  entangled  in  an  electric-light 
scheme.  He  said  that  he  gave  light,  —  not  sparks  of  the 
cat-and-dog  order,  but  that  he  himself  had  only  to  be  elec- 
trified, and  he  would  become  a  perfect  illumination.  He 
called  it  a  "•  beatification  ;  "  and  furthermore,  with  all  the 
vigor  of  the  man  who  prophesies  that  by  next  Christmas 


126  TIIE  AGE   OF  ELECTRICITY. 

gas  will  be  extinct  in  every  dwelling  in  the  land,  he  assev- 
erated that  a  glory  would  form  around  his  head,  just  like 
the  rings  or  miniature  auroras  represented  by  painters 
about  the  heads  of  saints.  It  is  all  solemnly  recorded  in 
4 '  Philosophical  Transactions."  Although  the  reader  may 
look  in  vain  through  that  erudite  work,  for  any  reference 
to  the  Boze  Electric  Light  Company  (limited),  this  re- 
markable announcement — to  quote  Priestley  once  more  — 
"  set  all  the  electricians  in  Europe  to  work,  and  put  them 
to  a  great  deal  of  expense." 

Among  these  electricians  was  Dr.  Watson ;  who,  having 
failed  to  see  why  there  should  be  such  a  thing  as  Boze 
electricity  any  more  than  cat  electricity  or  dry-dog  electri- 
city,—  or,  in  other  words,  disbelieving  Boze's  whole  story, 
—  caused  himself  to  be  electrified  while  perched  on  a  huge 
cake  of  pitch,  just  as  Boze  described.  He  candidly 
admitted,  that,  so  far  as  he  was  concerned,*  he  felt  the 
skin  of  his  head  tingle,  and  the  rather  disagreeable  sensa- 
tion of  things  creeping  over  him  ;  but  despite  his  remain- 
ing, with  exemplary  patience,  several  hours  in  the  dark, 
under  these  not  wholly  pleasant  conditions,  no  truthful 
person  could  be  found  who  for  a  single  moment  would 
admit  that  any  light  was  visible. 

It  is  perhaps  as  well  that  the  argument  which  Watson 
thereupon  addressed  to  Boze  is  not  set  down.  Ultimately, 
however,  Boze  confessed  that  he  had  dressed  himself  in  a 
suit  of  metal  armor  covered  with  points,  many  of  which 
radiated  from  the  helmet,  and  the  sparks  were  produced 
from  these  in  the  usual  way  (brush  discharge)  when  a 
strong  charge  was  conducted  to  them. 

There  was  a  poetic  justice  in  the  penalty  inflicted  on 
Boze.  He  claimed  afterwards  to  have  discovered  that  he 
could  invert  the  poles  of  a  magnet  "by  electricity  only, 
to  destroy  their  virtue,  and  restore  it  again."  He  did  net 


THE  ELECTRIC  LIGHT.  127 

describe  his  method :  what  it  may  have  been,  or  how  far 
it  may  have  foreshadowed  the  electro-magnet,  no  one 
knows.  He  got  no  hearing,  apparently,  from  the  Royal 
Society  ;  and  his  chronicler  contemptuously  remarks,  that, 
"  considering  that  no  person  in  England  could  succeed  in 
this  attempt,  and  that  we  are  now  (17G9)  able  to  do  it  but 
imperfectly,  it  is  hardly  probable  that  he  did  it  at  all." 
And  that  was  the  fate  of  the  first  philosopher  who  pre- 
tended that  he  had  an  electric  light  which  he  did  not  have, 
and  who  put  the  other  philosophers  u  to  a  great  deal  of 
expense." 

In  1745  Mr.  Gottfried  Gummert  of  Biala,  Poland,  in 
order  to  observe  whether  a  tube  from  which  the  air  was 
exhausted  would  give  light  when  it  was  electrified,  as  well 
as  when  it  was  excited,  presented  one,  some  eight  inches 
in  length  and  about  a  third  of  an  inch  in  diameter,  to  the 
electrified  conductor  of  a  machine.  He  was  surprised  to 
find  the  light  dart  vividly  the  whole  length  of  the  tube. 
This  light  in  vacuo,  Gummert  proposed  to  make  sse  of 
"  in  mines  and  places  where  common  fires  and  other  lights 
cannot  be  had."  This  appears  to  have  been  the  first 
announcement  of  the  discovery,  that,  by  rarefying  the 
air,  the  discharging  distance,  or  the  space  over  which  the 
spark  will  pass,  is  augmented,  while  the  discharge  itself  is 
caused  to  pass  silently.  It  is  now  known  that  every  atten- 
uated gas  has  its  own  color  when  traversed  by  the  dis- 
charge, and  that  the  rosy  color  of  the  light  seen  when 
rarefied  air  is  used  is  due  to  the  nitrogen  of  our  atmos- 
phere. The  same  color  appears  in  the  aurora  borealis, 
which  has  the  same  origin.  Tubes  containing  attenuated 
gas  are  called  vacuum  or  Geissler  tubes.  Their  light  is 
faint,  and  has  not  been  practically  applied  as  yet  to  illu- 
minating purposes.  Many. of  the  phenomena  observed 
with  these  tubes  remain  unexplained. 


128  THE  AGE   OF  ELECTRICITY. 

Referring  to  other  modes  of  causing  electric  illumination, 
Priestley,  writing  in  1769,  says,  "A  variety  of  beautiful 
appearances  may  be  exhibited  by  means  of  the  electrical 
light,  even  in  the  open  air  if  the  room  be  dark.  Brushes 
of  light  from  points  electrified  positively  and  not  made 
very  sharp,  or  from  the  edges  of  metallic  plates,  diverge 
in  a  very  beautiful  manner,  and  may  be  excited  to  a  great 
length  by  presenting  to  them  a  finger  or  the  palm  of  the 
hand." 

The  first  voltaic  pile  was  constructed  in  1800.  Eight 
years  later  Humphry  Davy  obtained  from  the  battery  of 
the  Royal  Institution,  the  first  electric  light  produced  by 
the  constant  galvanic  current.  This  battery  consisted  of 
two  thousand  cells,  arranged  in  two  hundred  porcelain 
troughs.  The  fluid  was  a  mixture  of  sixty  parts  of  water 
with  one  of  nitric  and  one  of  sulphuric  acid.  The  plates 
were  zinc  and  copper,  square  in  form,  and  thirty-two 
square  inches  in  surface.  "  When  pieces  of  charcoal," 
says  Davy,  "  about  an  inch  long  and  one-sixth  of  an  inch 
in  diameter,  were  brought  near  each  other  (within  the 
thirtieth  or  fortieth  part  of  an  inch) ,  a  bright  spark  was 
produced,  and  more  than  half  the  volume  of  the  charcoal 
became  ignited  to  whiteness  ;  and,  by  withdrawing  the 
points  from  each  other,  a  constant  discharge  took  place 
through  the  heated  air  in  a  space  equal  at  least  to  four 
inches,  producing  a  most  brilliant  ascending  arch  of  light, 
broad  and  conical  in  form  in  the  middle." 

Davy  used  pencils  of  common  charcoal,  which  wasted 
away  rapidly  ;  and  as  no  means  of  regulating  the  distance 
between  them  had  been  devised,  the  light  was  of  short 
duration.  For  some  thirty  years,  the  production  of  the 
voltaic  arc  remained  an  interesting  though  fruitless  labora- 
tory experiment.  The  power  derived  from  available  bat- 
teries was  weak  ;  their  construction  was  expensive  ;  and 


THE  ELECTRIC  LIGHT.  129 

these  difficulties  were  added  to  the  lack  of  proper  carbons 
and  of  controlling  apparatus  therefor.  In  1836  Grove's, 
and  in  1842  Bunsen's,  batteries  were  invented.  In  Grove's 
cell  the  attacked  electrode  is  zinc  plunged  in  dilute  sulphu- 
ric acid,  and  contained  in  a  porous  jar  ;  in  the  outer  vessel 
is  platinum  immersed  in  nitric  or  nitro-sulphunc  acid. 
Bunsen's  cell  has  already  been  described.  Both  of  these 
batteries  give  a  high  electro-motive  force ;  their  currents 
were  therefore  better  adapted  to  overcome  the  resistance 
of  the  carbons  and  the  intervening  air  space  than  those  of 
any  cells  previously  invented. 

In  1844  Le*on  Foucault  replaced  the  slides  of  common 
charcoal,  used  since  Davy's  time,  with  pieces  of  gas  car- 
bon, and  employed  the  Bunsen  cell  as  a  current-generator. 
He  also  contrived  a  means  of  regulating  the  lamp  by  hand. 
With  this  apparatus  M.  Deleuil  took  photographs  ;  and  in 
French  treatises  he  is  often  accorded  the  credit  of  being 
the  first  person  to  use  the  electric  light  for  such  a  purpose. 
This,  however,  is  not  the  fact.  In  November,  1840,  Prof. 
B.  A.  Silliman,  jun.,  and  Dr.  W.  H.  Goode  obtained  "pho- 
tographic impressions  by  galvanic  light  reflected  from 
the  surface  of  a  medallion  to  the  iodized  surface  of  a 
daguerrotype  plate,"  using  the  large  battery  of  nine  hun- 
dred cells  belonging  to  the  laboratory  of  Yale  College. 
Two  pictures  were  obtained  :  one  ' '  made  up  of  a  blur  or 
spot  produced  by  the  light  from  the  charcoal  points,  the 
image  of  the  retort-stand  on  which  a  medallion  of  white 
plaster  rested,  and  the  image  of  the  medallion;"  the 
other  picture  was  of  the  medallion  only.  An  interesting 
account  of  this  experiment  was  published  in  the  Journal 
of  the  Franklin  Institute  in  1843. 

One  evening  in  December,  1844,  during  a  thick  fog,  the 
people  who  were  passing  the  Place  de  la  Concorde  in  Paris 
were  astonished  by  suddenly  finding  that  they  could  see 


130  THE  AGE  OF  ELECTRICITY. 

clearly,  although  the  gas-lamps  at  a  distance  of  a  few  yards 
were  invisible.  A  very  intense  light  traversed  the  atmos- 
phere, and  illuminated  even  the  remotest  corners  of  the  vast 
square.  This  was  an  electric  light,  and  the  occurrence  is 
believed  to  mark  the  first  illumination  of  a  public  thorough- 
fare therewith.  The  Parisians  were  more  than  delighted 
with  the  magnificence  of  the  light.  In  rapid  succession 
electric  lamps  were  established  on  the  Pont  Neuf  to  illu- 
minate the  Seine  beneath,  on  the  Arc  de  Triomphe,  in  the 
court  of  the  Palais  Royal,  and  at  the  Porte  St.  Martin. 
It  was  simply  necessary  for  an  inventor  to  allege  that  he 
had  a  new  form  of  lamp,  to  secure  a  public  trial.  With 
characteristic  ingenuity  the  scenic  artists  of  the  opera 
seized  upon  the  light  as  a  means  of  introducing  new  and 
startling  effects  into  the  mise  en  scene.  Rossini's  "  Moses  " 
was  put  on  the  stage,  on  a  scale  of  great  magnificence  ; 
and  the  beams  of  the  electric  light  were  shed  upon  the 
figure  of  the  inspired  prophet,  investing  him  with  a  super- 
natural radiance.  In  the  final  scene,  the  spectrum  of  the 
light  was  used  to  imitate  the  rainbow.  The  Israelites 
were  grouped  on  the  front  of  the  stage  ;  while  in  the  far 
distance,  the  Egyptians,  immersed  in  partial  darkness,  are 
seen  perishing  in  the  waters.  Moses,  upon  a  high  rock, 
holds  the  tables  of  the  Law.  The  light,  gradually  increas- 
ing, represents  the  break  of  day ;  at  the  same  moment,  as 
the  symbol  of  the  new  covenant,  a  rainbow  appears.  One 
lamp  was  placed  behind  the  rock  in  the  foreground,  and 
its  light  concentrated  upon  the  characters ;  the  rest  of  the 
stage  being  in  obscurity.  The  beam  of  a  second  lamp, 
after  dispersion  by  a  prism,  painted  itself  as  a  rainbow 
upon  the  scene  at  the  back. 

The  mode  of  producing  the  voltaic  arc  is  quite  simple. 
The  two  rods  of  carbon  are  first  placed  in  contact.     The 


THE  ELECTRIC  LIGHT.  131 

current  then  passes  from  one  to  the  other ;  and  while  it  is 
so  passing,  the  rods  are  gradually  separated.  During  this 
action,  the  current  heats  the  air,  and  also  vaporizes  a  por- 
tion of  the  conductor,  so  that  the  interval  between  the  rods 
becomes  filled  with  carbon  probably  in  a  gaseous  state. 
This  carbon  vapor,  while  it  conducts  the  current,  offers  a 
high  resistance.  It  becomes  white  hot.  The  plus  carbon 

—  or  that  from  which  the  current  flows — is  usually  the 
uppermost,  and,  being  the  more  highly  heated  by  the  cur- 
rent, burns  away  most  rapidly  :  particles  of  this  carbon  are 
carried  off,  and  transferred  to  the  negative  carbon,  which 
thus  assumes  the  form  of  a  pointed  cone,  while  the  plus 
carbon  forms  a  hollow  crater  of  intense  brightness,  and 
acts  as  a  sort  of  reflector  to  throw  a  large  proportion  of 
the  light  downward. 

The  temperature  of  the  arc  is  immensely  high,  and  is 
the  most  intense  of  all  artificial  sources  of  heat.  "  Plati- 
num," wrote  Davy,  in  the  account  which  he  has  left  of 
his  famous  experiment,  "  was  melted  as  readily  as  wax 
in  the  flame  of  a  common  candle  :  quartz,  the  sapphire, 
lime,  magnesia,  all  entered  into  fusion."  The  diamond 

—  a  very  refractory  body  —  when  placed  in  the  arc  be- 
comes white  hot,  swells  out,  fuses,  and  gradually  trans- 
forms into  a  black  crumbling  mass.    Carbon  itself  has  been 
softened  so  that  it  can  be  easily  bent  and  welded.     The 
temperature  of  the  arc  is  estimated  at  about  8700°  Fah.  ; 
but  this  is  not  settled.     In  point  of  brilliancy,  it  is  rather 
less  than  one-third  as  bright  as  the  sun.     Its  characteristic 
color  is  a  bluish  white  ;  the  carbons  giving  a  white  light, 
and  the  arc  a  bluish  purple.     The  effect  is  rather  ghastly, 
owing  to  the  excess  of  blue  rays.     The  light  may  be  pro- 
duced not  only  in  air,  but  also  under  the  surface  of  water 
and  other  non-conducting  liquids,  in  oils,  and  in  a  vacuum  ; 
so  that  it  appears  to  be  due  to  the  incandescence,  and  not 


132  THE  AGE   OF  ELECTRICITY. 

to  the  oxidation,  of  the  carbon.  The  pressure  of  the 
current  required  to  maintain  an  arc  one-tenth  of  an  inch 
in  length  is  sixty  volts,  increasing  quickly  up  to  a  quarter 
of  an  inch,  and  after  that  at  the  rate  of  fifty-four  volts 
per  inch.  To  supply  such  high  pressure,  obviously,  a 
large  number  of  battery  cells  would  be  required,  with 
attendant  large  expense  due  to  the  consumption  of  zinc. 
All  the  early  arc  lamps  were  thus  supplied. 

Inasmuch  as  the  carbon  rods  slowly  burn  away,  it  is 
necessary  that  one  of  them  should  be  continuously  fed 
forward  by  suitable  machinery,  so  as  to  keep  the  resist- 
ance of  the  arc  as  constant  as  possible.  Upon  the  uni- 
form working  of  this  feeding  mechanism,  greatly  depends 
the  steadiness  of  the  light.  A  great  many  different  forms 
of  apparatus  for  this  purpose  exist.  We  shall  therefore 
refer  to  but  a  few  of  the  most  typical  forms. 

For  street  illumination,  it  is  important  that  the  lamp 
should  give  a  steady  light.  In  construction  it  should  be 
not  too  heavy  to  be  supported  by  an  ordinary  lamp-post, 
and  it  is  important  that  the  mechanism  should  all  be  above 
the  lamp  so  that  no  shadows  may  be  cast  downward. 

In  the  Brush  lamp,  the  feed  is  actuated  by  gravity  as 
will  be  understood  from  the  diagram  of  the  lamp  mechan- 
ism (Fig.  69).  The  upper  carbon  A  descends  by  its  own 
weight  until  it  meets  the  lower  one  B.  Then  the  current, 
moving  in  the  direction  of  the  arrows,  is  established,  and 
passes  between  the  carbons,  and  through  the  coil  C  of  a 
hollow  electro-magnet.  In  this  magnet  is  a  soft  iron, 
plunger  Z),  which,  when  the  magnet  is  excited,  is  drawn 
upward.  Through  the  intervention  of  a  lever  and  an 
ingenious  annular  clutch  at  E,  surrounding  the  rod  of  the 
upper  carbon  A  like  a  washer,  the  upper  carbon  is  lifted 
away  from  the  lower  carbon,  and  thus  the  arc  is  established. 

As  the  carbons  burn  away,  the  arc  has  a  tendency  to 


THE  ELECTRIC  LIGHT. 


133 


become  longer ;  and  this,  by  reducing  the  strength  of  the 
current,  diminishes  the  supporting  power  of  the  coil  C. 
The  latter  then  allows  its  plunger  to  descend,  thus  lower- 
ing the  carbon,  and  so  shortening  the  arc  until  the  proper 
strength  of  the  current  is  restored,  when  the  rising  of  the 
plunger  once  more  holds  the  carbon  in  position.  There  is 
also  an  ingenious  contrivance  whereby  each  lamp  in  a  cir- 
cuit is  enabled  to  .control  itself  independently  of  the  action 
of  all  the  others  in  the  circuit.  Ordinary  Brush  lamps 
such  as  are  used  for  street-lighting  give  a  light  equal  to 
that  of  about  eight  hundred  candles  ;  but  very  large  ap- 


JJyncuno 


Fig.  69. 

paratus  of  this  kind  has  been  made,  in  which  the  carbons 
are  three  and  a  half  inches  in  diameter,  giving  a  light 
equal  to  that  of  a  hundred  and  fifty  thousand  candles. 
An  ordinary  Brush  street-light  such  as  is  used  in  New- 
York  City  is  represented  in  Fig.  70. 

The  Siemens  lamp  depends  on  what  is  termed  the  differ- 
ential principle,  which  is  illustrated  in  the  diagram,  Fig. 
71.  Here  the  lower  carbon  B  is  stationary.  The  upper 
carbon  A  is  attached  to  the  end  of  a  rocking  arm  or  lever 
O,  at  the  other  end  of  which  is  a  core  D  of  soft  iron. 


134 


THE  AGE  OF  ELECTRICITY. 


This  core  enters  two  coils  E  and  F,  one  above  and  the 
other  below  the  lever.  The  coil  E  offers  a  high  resistance 
to  the  current,  because  it  is  of  fine  wire.  The  coil  jP,  on 
the  other  hand,  is  of  thick  wire,  and  offers  little  resistance. 
The  current,  starting  from  the  dynamo,  goes  by  a  wire 

to  the  point  G.  It  may 
now  take  either  of  two 
roads,  —  through  the  coil 
F,  the  lever  C,  and  the 
carbons  AB,  and  so  by  the 
wire //back  to  the  dynamo, 
thus  completing  the  circuit ; 
or  it  may  pass  through  the 
coil  E,  and  thence  by  the 
wire  G  to  the  wire  /T,  and 
so  to  the  dynamo,  —  in  this 
case,  not  passing  through 
the  carbons  at  all.  Now, 
the  current  having  two  pos- 
sible paths  will  divide  itself 
through  both,  the  most 
current  going  through 
the  path  which  offers  the 
least  resistance.  If  we 
suppose  that  at  the  out- 
set the  carbons  are  wholly 
separated,  then  there  is  a 
very  great  resistance  in 
the  first  of  the  paths  above  noted  :  consequently  the  cur- 
rent will  flow  around  the  other  path.  But  in  passing 
through  the  coil  E,  it  converts  that  coil  into  a  magnet, 
which  draws  up  the  core  D;  and  when  the  core  D  is 
drawn  up,  the  outer  end  of  the  lever  C  moves  down,  and 
thus  the  carbons  are  brought  into  contact.  Then  the 


Fig.  70. 


THE  ELECTRIC  LIGHT. 


135 


current  is  free  to  pass  through  the  carbons  ;  and  it  does 
so  until  they  become  burned  away,  too  widely  separated, 
and  hence  the  space  between  them  offers  so  much  resist- 
ance to  the  current  that  the  latter  again  travels  through 
the  coil  E,  and  so  causes  the  lever  C  to  bring  the  carbons 
nearer  together  again.  When  the  current  passes  through 
the  coil  F,  which  it  does  when  supplying  the  carbons,  this 
coil  also  acts  as  a  magnet  to  move  the  lever  in  the  oppo- 
site direction  to  that  in  which  it  is  moved  by  the  coil  E. 
The  actions  of  the 
two  coils  balance  each 
other  when  the  resist- 
ance of  the  arc  is 
uniform. 

The  two  lamps 
above  described  are 
types  of  the  two  prin- 
cipal systems  in  use. 
The  Brush  lamp  is 
based  on  what  is  termed 
the  gravity  plan,  where- 
in, as  we  have  seen, 
the  weight  of  one  carbon  causes  its  approach  to  the  other, 
and  the  magnetism  of  the  current  acts  against  this  to 
separate  the  carbons.  The  Siemens  lamp,  on  the  other 
hand,  is  constructed  on  the  differential  system  ;  the  differ- 
ence between  the  opposite  actions  of  the  two  magnets 
being  utilized  to  control  the  carbon. 

For  light-house  purposes,  it  is  of  course  absolutely 
necessary  that  the  light  shall  never  be  extinguished  for 
an  instant,  and  that  the  mechanism  shall  be  very  strong. 
Expense,  weight,  and  bulk  are  matters  of  no  moment ; 
and  slight  pulsations  of  the  light  are  not  a  serious  defect. 
For  this  use,  a  comparatively  old  form  of  lamp,  the 


Dynamo 


Fig.  71. 


136  THE  AGE  OF  ELECTRICITY. 

Serrin,  is  still  employed.  As  the  light  must  be  kept  in 
the  focus  of  the  reflector,  both  carbons  are  fed  forward ; 
this  being  effected  by  clock-work  mechanism  actuated  by 
the  weight  of  the  upper  carbon,  so  that,  as  the  upper 
carbon  descends,  the  lower  one  rises  to  meet  it. 

Hitherto  we  have  referred  simply  to  the  lamps  which 
are  known  as  "  arc  lamps,"  and  which,  as  has  been  seen, 
depend  upon  the  production  of  the  voltaic  arc  between 
the  ends  of  separated  carbon  rods.  These  constitute  one 
principal  class.  Another  class  of  electric  lamp,  of  much 
greater  importance,  —  for  its  applicability  is  far  wider,  — 
is  the  incandescent  lamp,  which  consists  of  a  thin  fila- 
ment or  wire  of  carbon  enclosed  in  a  glass  globe  from 
which  the  air  has  been  exhausted. 

The  idea  of  using  a  body  rendered  incandescent  by  the 
heating  action  of  a  current,  as  a  means  of  illumination, 
appears  to  have  been  first  described  by  Mr.  Frederic  de 
Moleyns,  who  in  1841  patented  in  England  an  electric 
lamp  in  which  a  platinum  wire  enclosed  in  an  exhausted 
glass  globe  was  to  receive  a  shower  of  plumbago  parti- 
cles. There  is  nothing  practicable  about  De  Moleyns' 
idea ;  and  it  would  doubtless  have  remained  forever  in 
oblivion,  had  not  the  English  writers  on  the  subject  found 
De  Moleyns'  patent  a  convenient  peg  on  which  to  hang  a 
claim  that  the  incandescent  electric  lamp  is  a  British  in- 
vention. The  real  inventor  of  the  lamp  appears  to  have 
been  J.  W.  Starr  of  Cincinnati,  O.  Starr  used  an  ex- 
hausted glass  globe  in  which  was  a  thin  strip  of  graphite 
held  between  two  clamps  affixed  to  a  porcelain  rod  ;  the 
latter  being  suspended  by  a  platinum  wire  sealed  in  the 
globe.  Starr  died  in  1847,  but  twenty-five  years  of  age  ; 
a  victim  to  overwork,  and  disappointment  in  his  endeavors 
to  perfect  this  lamp  and  a  magneto-electric  machine  to 
drive  it.  It  gave  an  excellent  light.  Starr  was  evidently 


THE  ELECTRIC  LIGHT.  137 

a  prophet  without  honor  in  his  own  country ;  for  his 
endeavors  to  interest  others  in  his  invention  met  with 
failure,  and  critics  were  not  wanting  who  openly  asserted 
that  he  was  simply  invoking  perpetual  motion.  This, 
apparently,  because  he  proposed  to  utilize  a  magneto- 
electric  machine  to  supply  his  lamp.  "The  Cincinnati 
Advertiser"  of  Sept.  4,  1844,  published  a  letter  from  a 
correspondent  who  stated  as  follows  :  — 

"  1.  That  this  light  is  magneto-electrical. 

"  2.  That  it  is  produced  by  permanent  magnets,  which 
may  be  increased  to  an  indefinite  extent.  The  apparatus 
now  finished  by  the  inventors  and  discoverers  in  this  case 
will  contain  twenty  magnets. 

"3.  That  it  supplies  a  light  whose  brilliancy  is  insup- 
portable to  the  naked  eye. 

"4.  That  a  tower  of  adequate  height  will  enable  a 
light  to  be  diffused  all  over  Cincinnati,  equal  for  practical 
purposes  to  that  of  day. 

"5.  That  this  light,  when  once  set  in  operation,  will 
continue  to  illuminate  without  one  cent  of  additional 
expense. 

"  6,  and  lastly.  That  the  inventors  in  this  process  have 
nearly  solved  the  long-sought  problem,  —  perpetual  mo- 
tion. ...  I  suppose  this  light  will  prove  the  greatest 
discovery  of  modern  times.  It  is  needless  to  add  how 
much  it  gratifies  me,  that  Cincinnati  is  the  place,  and  two 
of  its  native  sons — J.  Milton  Sanders  and  John  Starr  — 
the  authors,  of  the  discovery." 

Starr  appears  thus  to  have  been  the  first  to  suggest  the 
lighting  of  cities  by  electric  lights  011  high  towers.  Shortly 
afterwards,  Mr.  W.  H.  Weekes  in  England  proposed  sup- 
plying lights  thus  elevated,  from  earth  batteries  formed 
of  huge  plates  of  zinc  and  copper  buried  beneath  the 
structures.  Several  years  before,  he  had  suggested  ele- 


138  THE  AGE  OF  ELECTRICITY. 

rating  oxyhydrogen  lights  in  the  same  way.  On  the 
strength  of  that  suggestion,  the  English  journals,  as 
usual,  claimed  Starr's  invention  as  British ;  and  when 
Starr's  patent  appeared,  in  1846,  they  insisted  that  it 
was  anticipated  by  De  la  Rive,  who  had  employed  coke 
cylinders  surrounded  by  rings  of  metal,  between  which 
rings  and  cylinders  the  arc  passed  ;  and  by  Grove,  who 
had  used  platinum  spirals.  Neither  Grove  nor  De  la 
Rive  enclosed  an  incandescent  carbon  rod  in  a  globe  ex- 
hausted of  air ;  but  a  small  difference  of  that  sort  did 
not  stand  in  the  way  of  denying  to  an  American  the  honor 
and  credit  that  was  his  due.  It  was  carrying  Sydney 
Smith's  sneering  comment,  "  Who  reads  an  American 
book  ?  "  a  little  farther  by  the  habitual  refusal  to  believe 
that  any  thing  good  whatever  could  come  out  of  the 
Nazareth  of  the  United  States. 

One  of  the  most  extraordinary  claims  to  the  honor 
of  the  same  invention  was  made  not  long  ago,  by  M.  de 
Changy,  who  asserted  that  as  far  back  as  1838  his  friend 
M.  Jobard  of  Brussels  suggested  the  idea  that  a  small 
carbon,  employed  as  a  conductor  of  a  current  in  a  vacuum, 
would  give  an  electric  lamp  with  an  intense  fixed  and 
durable  light.  Acting  on  this  suggestion,  De  Changy  in- 
vented several  forms  of  lamps,  using  platinum  spirals,  and 
even  devised  systems  for  the  electric  lighting  of  mines, 
luminous  buoys,  submerged  lamps  for  fishing,  and  nauti- 
cal telegraphy  by  means  of  colored  tubes  containing  the 
incandescent  wires.  The  whole  matter  was  brought  be- 
fore the  French  Academy  of  Sciences  ;  and  a  commission, 
of  which  M.  Desprez  was  the  chief,  was  appointed  to 
examine  the  invention.  De  Changy  claimed  to  have  suc- 
ceeded at  this  time  in  arranging  several  lamps  in  one  cir- 
cuit, which  could  be  lighted  simultaneously  in  groups,  or 
separately  without  affecting  the  normal  intensity  of  each. 


THE  ELECTRIC  LIGHT.  139 

Desprez  wrote  for  a  detailed  account  of  the  invention  ; 
which  was  declined  by  Jobard,  on  the  ground  that  the 
exposure  would  affect  a  pending  patent.  Thereupon 
Desprez — with  that  singular  fatuity  concerning  patents, 
now  happily  confined  to  medical  practitioners  —  said  that 
De  Changy  evidently  desired  to  make  money  out  of  his 
invention,  and  so  did  not  merit  the  name  of  savant,  and 
that  the  Academy  had  no  further  interest  in  his  work. 
This  so  disheartened  De  Changy,  that  he  abandoned  his 
labors,  and  as  a  consequence,  —  if  his  statements  be  cor- 
rect,—  the  incandescent  light  was  lost  to  the  world  for 
more  than  a  quarter  of  a  century.  In  that  interval,  how- 
ever, the  Academy  changed  its  views.  It  decreed  the 
award  of  the  Volta  prize  to  Mr.  Alexander  Graham  Bell, 
upon  his  claim  to  the  invention  of  the  speaking  telephone, 
—  an  instrument  which  has  yet  to  be  given  freely  to  the 
world. 

The  incandescent  lamp  which  forms  one  of  the  great 
classes  of  electric  illuminating  devices,  as  now  constructed, 
consists  of  a  thin  filament  or  wire  of  carbon  enclosed  in 
a  glass  globe  from  which  the  air  has  been  exhausted. 
When  a  current  of  electricity  of  suitable  strength  passes 
through  the  filament,  it  becomes  white  hot,  or  incandes- 
cent, and  so  yields  a  light  of  from  one  to  one  hundred 
candles,  according  to  its  surface,  and  for  a  given  surface 
according  to  the  temperature  to  which  it  is  raised.  There 
are  many  forms  of  incandescent  lamps,  differing  mainly 
in  detail  and  more  especially  in  the  mode  of  preparing  the 
carbon  filaments.  New  forms  are  constantly  appearing. 
In  all  of  these,  however,  the  filament  is  of  vegetable  fibre, 
carbonized  by  heat.  The  ends  of  this  filament  are  con- 
nected to  two  platinum  wires  which  pass  through  a  neck 
formed  on  the  globe.  These  are  melted  into  the  glass 
itself ;  and  platinum  is  chosen  because  it  expands  by  heat 


140  THE  AGE  OF  ELECTRICITY. 

at  about  the  same  rate  as  the  glass  itself  does,  so  that  the 
latter  does  Dot  crack  in  cooling.  The  exhaustion  of  the 
air  in  the  globe  must  necessarily  be  as  nearly  perfect  as 
possible.  Without  the  Sprengel  air-pump,  it  would  prob- 
ably be  impracticable  to  produce  an  efficient  vacuum. 
This  pump  consists  of  glass  tubes,  down  which  mercury 
flows  in  a  broken  stream  or  in  drops.  Near  the  top  of 
the  tubes  are  side  openings  connected  to  the  chamber  to 
be  exhausted.  Air  enters  from  this  chamber,  and,  becom- 
ing compressed  between  consecutive  mercury  drops,  is 
carried  away ;  and  the  process  is  repeated  until  the  cham- 
ber is  completely  exhausted.  While  the  lamp  is  still  at- 
tached to  the  pump,  a  current  of  electricity  is  sent  through 
the  filament,  sufficient  to  raise  it  to  a  somewhat  higher 
degree  of  incandescence  than  will  be  used  in  actual  work. 
All  the  gas  driven  out  of  the  carbon  is  at  once  removed 
by  the  pump,  and  the  lamp  is  sealed  while  the  current  is 
still  passing. 

The  incandescent  lamps  in  most  general  use  are  respec- 
tively those  devised  by  Edison  and  Swan,  and  these  may 
be  taken  as  typical.  Mr.  Edison's  experiments  upon  the 
materials  and  construction  of  incandescent  lights  are  prob- 
ably the  most  elaborate  and  far-reaching  ever  conducted. 
On  the  other  hand,  it  is  doubtful  whether  any  inventor 
ever  undertook  an  investigation  more  abundantly  provided 
with  the  means  for  carrying  it  to  successful  termination. 
He  began  by  studying  conductors  made  of  an  alloy  of 
platinum  and  indium,  and  also  of  platinum  alone  ;  but 
found  that  the  effect  of  incandescence  upon  the  wires  ex- 
perimented upon  was  to  produce,  all  over  their  surface, 
innumerable  cracks,  and  in  a  few  hours  these  fissures 
united,  and  the  wire  fell  to  pieces.  With  characteristic 
ingenuity  he  contrived  a  way  of  heating  the  wires  by  a 
current  in  vacuo  so  as  actually  to  weld  together  the  edges 


THE  ELECTRIC  LIGHT.  141 

of  these  minute  cracks  ;  and  finally  succeeded  in  producing 
metals  in  a  state  such  as  had  never  been  known  before, 
increasing  their  hardness  and  density  to  an  extraordinary 
degree,  and  raising  their  fusing- points  so  high  that  they 
remained  unaffected  at  temperatures  at  which  most  sub- 
stances would  be  melted  or  consumed,  and  very  many 
would  be  converted  into  vapor.  By  his  process  he  ren- 
dered platinum  wire  competent  to  yield  a  light  of  twenty- 
five  standard  candles  ;  while  the  same  wire  not  treated 
would  give  a  light  of  not  more  than  four  candles  before 
it  fused. 

Ingenious  as  this  discovery  was,  it  did  not  solve  the 
problem.  The  inventor  then  turned  his  attention  to  car- 
bon, —  that  extraordinary  substance  which  was  already 
playing  the  principal  part  in  the  operation  of  the  speaking 
telephone,  the  galvanic  battery,  and  the  voltaic  arc  light. 
As  usual,  he  carbonized  about  every  thing  within  reach,  — 
"cotton  and  linen  thread,  wood  splints,  paper  coiled  in 
various  ways,  also  lamp-black,  plumbago,  and  carbon  in 
various  forms,"  in  his  endeavor  to  make  a  carbon  filament 
or  wire.  Later  on  he  settled  upon  paper, —  "Bristol 
board," — which  he  punched  into  narrow  elliptical  strips. 
Finally  he  determined  that  the  carbon  should  be  purely 
structural  in  character ;  that  is,  its  natural  structure,  cell- 
ular or  otherwise,  should  be  preserved  unaltered,  and  not 
modified  by  any  treatment  "  which  tends  to  fill  up  the  cells 
or  pores  with  unstrtictural  carbon,  or  to  increase  its  den- 
sity, or  alter  its  resistance."  Farther  on  we  shall  see  that 
just  the  opposite  view  is  taken  by  the  inventor  of  the 
Swan  lamp ;  and  the  curious  fact  is  presented,  of  two 
forms  of  the  same  apparatus,  both  fairly  successful,  yet 
dependent  on  radically  opposite  deductions  from  experi- 
ment. 

The  fibre  now  used  in  the  Edison  lamps  is  that  of  a 


142 


THE  AGE  OF  ELECTRICITY. 


grass  from  South  America,  called  ' '  monkey-bast ; ' '  each 
blade  of  which  is  generally  round,  and  composed  of  a 
great  number  of  elementary  fibres  held  together  by  a  nat- 
ural cement  or  resin,  which,  carbonizing,  locks  all  the  ele- 
mentary fibres  together  into  a  homogeneous  filament.  The 
ordinary  form  of  Edison  lamp  is  represented  in  Fig.  72. 
The  ends  of  the  carbon  filament  are  connected  to  platinum 
wires,  and  these  are  attached  to  a  screw,  and  a  sole  plate 
stamped  from  thin  copper,  and  insulated  from  each  other 
by  plaster-of-paris,  which  surrounds  the 
neck  of  the  envelope,  and  forms  a  firm 
and  rigid  attachment.  The  socket  into 
which  this  fitting  screws  is  simply  a 
counterpart  of  the  thread  on  the  lamp. 

In  lieu  of  using  a  so-called  structural 
carbon,  Mr.  Swan  in  his  lamp  prefers  a 
filament  as  far  as  possible  devoid  of  struc- 
ture. He  steeps  a  cotton  thread  in  a  solu- 
tion of  sulphuric  acid  and  water  until  the 
tissue  is  entirely  destroyed,  and  a  horny 
homogeneous  filament  is  produced,  which 
before  carbonization  is  rendered  uniform 
in  density  by  compression.  Fig.  73  repre- 
sents the  present  form  of  Swan  lamp. 
Tue  filament  is  connected,  as  usual,  to  platinum  wires, 
which  terminate  outside  the  neck  of  the  globe,  in  small 
loops.  The  globe  is  entirely  separate  from  the  holder ; 
the  latter  being  of  ebonite,  provided  with  a  screw  plug 
for  attachment  to  the  fixture.  On  the  side  of  the  holder 
are  binding  posts  for  the  connection  of  the  circuit  wires. 
These  posts  communicate  with  platinum  hooks,  which 
engage  the  loops  of  the  globe  wire.  The  neck  of  the 
globe  rests  in  a  spiral  spring,  which  steadies  it,  and  at 
the  same  time  causes  a  slight  strain  on  the  hooks,  so  that 


cig.  72. 


THE  ELECTRIC  LIGHT. 


143 


the  hooks  and  loops  make  a  very  excellent  electrical  joint. 
The  whole  arrangement  is  about  the  neatest  and  most 
elegant  which  has  thus  far  been  devised  for  the  purpose. 
The  form  of  the  Swan  filament  is  distinctive,  it  being 
shaped  in  a  spiral. 

M.  Muthel,  a  German 
inventor,  has  made  an 
incandescent  lamp 
which  requires  no  vacu- 
um in  the  globe.  He 
makes  a  wire  of  a  mix- 
ture of  bodies  which 
are  conductors  and  non- 
conductors of  electrici- 
ty, in  which  fusion  is 
wholly  overcome ;  the 
non-conducting  sub- 
stances preventing  the 
melting  of  the  metallic 
parts.  It  is  supposed 
that  the  electric  spark 
jumps,  so  to  speak, 
from  one  particle  to 
another,  and  in  this 
way  causes  a  heating 
of  the  other  substances, 
which,  being  brought 
to  incandescence,  emit 
a  more  intense  light. 

There  are  two  ways  of  arranging  electric  lamps  in  order 
to  distribute  the  current  to  them.  They  can  be  placed 
one  after  another  in  a  single  circuit  or  wire  connecting  the 
two  poles  or  brushes  of  the  generator  ;  as  shown  in  Fig.  74, 
where  M  is  the  generator  or  machine,  and  LL  the  lamps. 


Fig.  73. 


144  THE  AGE  OF  ELECTRICITY. 

In  this  case  the  current  requires  to  have  a  high  electro- 
motive force  in  order  to  overcome  the  added  resistances 
of  the  whole  number  of  lamps.  Such  a  current  is  supplied 
by  the  Brush  generator  or  the  peculiar  form  of  Gramme 
generator  employed  by  Jablochkoff.  The  other  way  of 
arranging  the  lamps  is  to  connect  them  singly  or  in  little 
groups  by  cross  wires  between  two  main  conductors  joined 
to  the  brushes  of  the  generator,  as  shown  at  LL  in  Fig. 


t,                    X) 

®        © 

"L                  L 

0 

M 

f: 

\ 

Fig.  74. 

75.  Then  the  current,  instead  of  traversing  one  lamp 
after  another,  splits  up  between  the  lamps,  part  going 
through  one  lamp  or  group,  and  part  through  another. 
The  resistance  of  any  particular  path  or  channel  for  the 
current  is  in  such  a  case  not  very  great,  and  the  electro- 
motive force  of  the  current  need  not  be  dangerously 
high.  It  is  on  this  plan  that  incandescent  lamps  are 
generally  arranged  for  domestic  purposes,  and  the  cur- 


* 


Fig.  75. 

rents  flowing  in  the  wires  about  a  house  would  of  course 
be  harmless.  These  lamps  can  be  mounted  on  an  ordinary 
chandelier. 

There  is  still  a  third  form  of  electric-light  apparatus, 
which,  however,  has  not  come  into  extended  use.  This 
is  known  as  the  incandescence  arc  system.  It  is  an  inter- 
mediate arrangement  between  the  arc  and  the  incandescent 
lights.  The  illumination  is  produced  by  the  passage  of 


THE  ELECTRIC  LIGHT.  145 

the  electric  current  through  a  rod  of  carbon  of  a  diameter 
so  small  that  its  extremity  becomes  heated  nearly  to  white- 
ness. This  is  one  of  the  oldest  forms  of  electric  light. 
It  was  originally  patented  in  England  in  1846. 

The  "  electric  candle,"  so  called,  is  a  very  re- 
markable form  of  arc  light  which  on  its  introduc- 
tion in  1878  created  great  popular  interest.  It 
probably  did  more  to  turn  the  attention  of  invent- 
ors to  the  possibilities  of  improving  the  electric 
light,  after  thirty  years'  neglect  of  the  subject, 
than  any  other  recent  invention,  excepting  proba- 
bly the  Gramme  dynamo.  It  was  originally  in- 
vented by  M.  Paul  Jablochkoff,  a  Russian  officer 
of  engineers  ;  and,  as  first  produced,  consisted  of 
two  carbon  rods  fixed  parallel  to  one  another,  a 
slight  distance  apart,  and  separated  by  an  insu- 
lating medium  which  is  consumed  at  the  same  rate 
as  the  carbons  themselves.  As  soon  as  the  cur- 
rent commences  to  pass,  the  voltaic  arc  plays 
across  the  free  ends  of  the  carbons.  The  ad- 
jacent insulating  material  becomes  consumed,  and 
slowly  uncovers  the  pair  of  carbons  just  as  the 
wax  of  a  candle  gradually  uncovers  the  wick. 

The  usual  form  of  Jablochkoff  candle  is  repre- 
sented   in   Fig.    76.     There   are   two   cylindrical 
carbons  about  nine  inches  long  by  sixteen-hun- 
dredths  of  an  inch  in  diameter.     The  insulating 
material  between  them  is  a  mixture  of  sulphate  of 
lime  and  sulphate  of  barytes.     As  a  candle  will 
last  but  for  about  two  hours,  it  is  necessary  to  ar- 
range several  of  them  in  a  holder,  so  that  the  total  period 
of  lighting  may  range  up  to  sixteen  hours.    Whatever  may 
be  the  number  of  candles  to  be  lighted,  one  after  another, 
to  afford  a  continuous  light  for  a  given  time,  it  is  neces- 


146  THE  AGE   OF  ELECTRICITY. 

sary  to  employ  a  device  by  which,  as  soon  as  one  candle 
has  burnt  out,  the  current  feeding  it  shall  be  switched  off 
to  the  one  adjacent.  This  is  effected  either  by  hand  or 
by  the  use  of  an  automatic  commutator. 

The  Soleil  light  stands  midway  between  the  electric 
candle  and  the  incandescence  arc  light.  It  has,  however, 
some  remarkable  characteristics  peculiar  to  itself.  A 
block  of  refractory  material,  such  as  marble,  lime,  or 
granite,  has  a  cavity  on  one  side,  shaped  like  a  truncated 
cone,  to  the  face  of  which  penetrate  the  carbons,  travers- 
ing the  mass  through  inclined  cylindrical  holes.  When 
the  arc  passes  between  the  two  points,  it  plays  on  the 
face  of  the  recess,  heats  it,  and  transforms  it  into  a  small 
crater,  whence  the  luminous  rays  escape  in  a  conical  beam. 
The  light  is  slightly  golden  in  color.  It  consumes  more 
power  than  many  arc  lights,  but  is  very  durable  and 
simple. 

When  a  conductor  conveying  a  powerful  electric  current 
is  suddenly  broken,  a  bright  flash,  called  the  extra  spark, 
appears  at  the  point  of  separation.  The  extra  spark  will 
appear,  although  the  current  is  not  sufficient  to  sustain  an 
arc  of  any  appreciable  length  at  the  point  of  separation. 
In  order  to  obtain  a  continuous  light  from  this  spark, 
Professors  Thomson  and  Houston  have  devised  an  appara- 
tus in  which  one  or  both  of  the  carbon  electrodes  are 
caused  to  vibrate  to  and  from  each  other,  so  as  to  touch 
momentarily  at  each  vibration.  These  motions  follow 
each  other  at  such  a  rate  that  the  effect  of  the  light  pro- 
duced is  continuous  ;  for,  as  is  well  known,  when  flashes 
of  light  follow  one  another  at  a  rate  greater  than  twenty- 
five  to  thirty  per  second,  the  effect  of  an  uninterrupted 
glow  is  produced. 

The  applications  of  the  electric  light  are  very  numerous. 
The  most  extensive  in  point  of  magnitude  which  has  been 


THE  ELECTRIC  LIGHT.  147 

proposed  is  the  establishment  of  an  electric  sun  of  eigh- 
teen-million-candle  power,  on  the  summit  of  a  tower 
twelve  hundred  feet  high,  for  the  illumination  of  Paris. 
For  military  use,  the  powerful  beams  of  the  arc  light  are 
employed  to  illuminate  fortifications  under  bombardment, 
or  reveal  the  approach  of  an  enemy.  Projectors  have 
been  devised  whereby  the  beam  can  be  given  a  range  of 
eighty-six  thousand  feet.  For  submarine  purposes,  the 
electric  light  is  of  great  value  :  it  has  been  employed  in 
removing  sunken  obstructions  in  the  Suez  Canal ;  for 
illuminating  the  sea  depths,  and  so  attracting  deep-sea 
fish  ;  and  for  lighting  floating  buoys.  This  last  applica- 
tion is  of  considerable  ingenuity.  By  the  motion  of  the 
buoy,  due  to  its  rise  and  fall  on  the  waves,  air  is  com- 
pressed within  the  buoy,  which  acts  intermittently  to  drive 
a  dynamo,  and  also  to  sound  a  whistle.  When  the  air 
reaches  a  certain  degree  of  compression,  the  dynamo 
rotates,  and  the  lamp  glows  brilliantly.  On  shipboard,  arc 
lamps  are  used  for  running  lights,  and  also  at  the  mast- 
heads of  steamers ;  and  incandescent  lights  illuminate 
between  decks.  The  steamship  "  Arizona,"  for  example, 
carries  two  dynamos  capable  of  supplying  six  hundred 
lights;  and  the  Sound  steamer  "  Pilgrim  "  is  fitted  with 
nine  hundred  and  twelve  incandescent  lamps. 

It  has  been  proposed  to  use  a  balloon  filled  with  hydro- 
gen, and  containing  inside  an  incandescent  lamp,  for  sig- 
nalling purposes  ;  the  whole  globe  becoming  illuminated 
whenever  the  lamp  glows.  For  lighting  carriages,  electric 
lamps  are  arranged  both  inside  and  beside  the  coachman's 
seat,  and  are  conveniently  fed  by  storage  batteries.  The 
arc  light  forms  an  excellent  head-light  for  locomotives  ; 
the  jarring  action  of  the  vehicle  being  prevented  by  con- 
trolling the  carbons  by  hydraulic  pressure. 

Electric  lights    of   immense   power   are   used  in   light- 


148  THE  AGE  OF  ELECTRICITY. 

houses.  The  condensed  beam  of  the  great  light  at  Souta 
Point,  England,  is  equal  in  power  to  eight  hundred  thou- 
sand candles.  The  South  Foreland  lights,  two  in  number, 
are  of  one  hundred  and  eighty  thousand  candle  power 
each. 

The  incandescent  electric  light  has  been  found  espe- 
cially useful  in  coal-mines,  where  the  fire-damp  atmosphere 
renders  the  presence  of  any  exposed  flame  exceedingly 
dangerous. 

In  medicine  the  electric  light  has  been  adapted  with 
various  forms  of  carrying  apparatus,  whereby  it  is  used 
to  illuminate  the   larynx,  the    stomach,   and  the 
cavities  of  the  mouth.     Combined  with  a  photo- 
graphic camera,  it  allows  of  accurate  photographs 
being  taken  of  diseased  parts  which  the  eye  can- 
not see.     Its  latest  application  is  to  the  ophthal- 
moscope.    Fig.  77  represents  one  of  the  miniature 
lamps  used  for  surgical  purposes.     Water  circu- 
lates in  the  space  between  the  lamp  itself  and  an 
outer  glass  tube,  to  keep  the  lamp  cool  enough  to  permit  of 
its  introduction  into  the  internal  parts  of  the  living  body. 
Miniature  lamps  have  also  been  set  in  brooches  and  shirt- 
studs,  and  made  to  form  the  petals  of  artificial  flowers. 
Sometimes  they  are  incased  in  masses  of  colored  glass  cut 
in  facets  to  imitate  jewels. 

During  the  political  campaign  of  1884,  as  part  of  one 
of  the  torchlight  processions,  quite  a  large  body  of  men 
marched  with  incandescent  lamps  on  their  heads.  The 
participants  formed  a  hollow  square,  in  the  middle  of 
which  was  a  large  dynamo  driven  by  a  forty-horse-power 
engine,  these  machines  being  on  trucks.  Steam  was  pro- 
vided from  the  boiler  of  a  large  steam  fire-engine.  The 
dynamo  current  was  conducted  through  copper  wires 
through  a  rope  some  twelve  hundred  feet  long.  At  inter- 


THE  ELECTRIC  LIGHT.  149 

vals  of  five  feet  along  the  rope  was  an  ordinary  cut-out, 
or  lamp-receptacle,  within  which  screwed  a  safety  catch 
carrying  two  wires  which  led  up  the  sleeve  of  the  person 
holding  the  rope  at  that  point,  and  through  the  back  of 
his  helmet  to  a  sixteen-candle-power  incandescent  lamp 
on  the  top  of  it.  Other  lamps  —  there  were  some  three 
hundred  in  all  —  were  distributed  on  the  trucks  and  on  the 
harness  of  the  horses.  The  effect  was  exceedingly  bril- 
liant and  novel. 

One  of  the  comicalities  of  the  electrical  exposition  of 
1884,  in  Philadelphia,  was  a  negro  who  distributed  cards, 
while  wearing  upon  his  helmet  a  very  brilliant  incandes- 
cent light.  Two  wires  led  from  the  lamp,  under  his  jacket, 
down  each  leg,  and  terminated  in  copper  disks  fastened 
to  his  boot-heels.  Squares  of  copper  of  a  suitable  size 
for  him  to  stand  naturally  upon  were  placed  at  intervals 
in  the  floor,  and  were  electrically  connected  with  the  dy- 
namo. Folks  from  the  rural  districts  inquired  cost,  as 
useful  to  have  around  the  house. 

For  theatrical  effects,  the  incandescent  electric  light  in 
its  various  forms  is  frequently  employed.  In  a  recent 
performance  of  "Faust"  in  England,  the  actor  personat- 
ing Mephistopheles  produced  the  most  unearthly  colors 
on  his  countenance  by  means  of  small  incandescent  lights 
contained  in  globes  of  various  colored  glass,  fastened 
beneath  the  visor  of  his  cap.  In  the  duel  scene  between 
Faust  and  Valentine,  in  which  Mephistopheles  takes  a 
sinister  part,  whenever  the  sword  of  the  demon  crossed 
that  of  Valentine,  a  continuous  flash  of  fire  appeared. 
The  combatants  had  a  metal  plate  under  foot,  connected 
with  a  battery  ;  and  both  Valentine  and  Mephistopheles 
wore  shoes  provided  with  metal  soles,  which  were  con- 
nected by  a  concealed  wire  with  their  sword-blades.  The 
continuous  discharge  of  electricity  was  produced  by  the 


150  THE  AGE  OF  ELECTRICITY. 

saw-like  edges  of  the  weapons,  each  tooth  giving  off  its 
spark.  For  ballets  and  fair}7  scenes,  small  incandescent 
lamps  are  fastened  on  the  heads  of  the  performers,  and 
are  supplied  by  storage  batteries  concealed  on  their  per- 
sons. In  the  aquatic  circus  in  Paris,  the  great  circular 
tank  of  water,  which  replaces  the  usual  ring,  is  illumi- 
nated by  submerged  electric  lamps.  When  all  other  lights 
in  the  auditorium  are  extinguished,  very  novel  and  curious 
effects  are  produced  by  swimmers,  representing  mermaids, 
naiads,  etc.,  moving  about  in  the  illuminated  water. 

A  series  of  important  experiments  were  conducted  by 
the  late  Sir  William  Siemens,  upon  the  influence  of  the 
electric  light  upon  vegetation.  He  fitted  up  in  his  large 
greenhouses  two  arc  lamps,  each  capable  of  emitting  a 
light  of  about  five  thousand  candle  power.  Among  the 
vegetables  planted  were  pease,  French  beans,  wheat, 
barley,  oats,  cauliflowers,  and  a  variety  of  berries  and 
flowering  plants.  It  was  found  that  the  electric  light  was 
capable  of  producing  upon  plants  effects  comparable  to 
those  of  solar  radiation  ;  that  chlorophyll  was  produced 
by  it,  and  that  bloom,  and  fruit  rich  in  aroma  and  color, 
could  be  developed  by  its  aid.  The  experiments  also  went 
to  prove  that  plants  do  not,  as  a  rule,  require  a  period  of 
rest  during  the  twenty-four  hours  of  the  day,  but  make 
increased  and  vigorous  progress  if  subjected  (in  winter 
time)  to  solar  light  during  the  day  and  to  electric  light 
during  the  night. 

Very  beautiful  effects  can  be  produced  by  the  aid  of  the 
electric  light  when  reflected  from  below  into  a  jet  of  water. 
By  simply  placing  pieces  of  colored  glass  before  the  lamp, 
the  jets  can  be  differently  colored,  so  that  the  appearance 
of  a  fountain  of  luminous  jewels  is  caused. 

It  was  for  a  long  time  believed  that  electric  lights  were 
far  inferior  to  oil  or  gas  lights  in  their  capacity  to  pene- 


THE  ELECTRIC  LIGHT.  151 

trate  fog.  Recent  investigations  have  shown,  however, 
that  the  advantage  in  favor  of  oil  and  gas  is  not  more 
than  one  per  cent. 

With  regard  to  the  energy  consumed  in  electric  lighting, 
in  Edison's  incandescence  system,  one  horse-power  of  work 
yields  from  99  to  189  candle  power  light ;  in  Swan's  sys- 
tem, about  150  candle  power.  With  existing  galvanic 
batteries,  the  yearly  cost  of  operating  incandescent  lamps 
is  about  seven  times  as  much  as  when  the  dynamo  is  em- 
ployed. A  good  incandescent  lamp  will  last  from  seven 
hundred  to  a  thousand  hours. 

Recent  electric-lighting  statistics  show  that  at  the  pres- 
ent time  (1886)  there  are  in  the  United  States  upwards  of 
ninety-five  thousand  arc  and  nearly  two  hundred  and  fifty 
thousand  incandescent  lamps,  distributed  in  over  four  hun- 
dred cities  and  towns.  Not  less  than  seventy  millions  of 
dollars  is  invested  in  the  business  of  electric  lighting  in 
this  country  alone.  In  Paris,  in  1878,  the  cost  to  the  city 
was  at  the  rate  of  twenty-nine  cents  per  hour  for  a  lamp 
of  from  five  hundred  to  seven  hundred  candle  power. 
The  city  of  New  York,  at  the  present  date,  pays  at  the 
rate  of  about  six  cents  per  hour  for  a  lamp  of  two  thou- 
sand candle  power. 


152  THE  AGE  OF  ELECTRICITY. 


CHAPTER    IX. 

ELECTRO-MOTORS,    AND   THE    CONVERSION    OF    ELECTRICAL 
ENERGY    INTO    MECHANICAL   ENERGY. 

THE  electro-motor,  or  electro-magnetic  engine,  is  an 
engine  driven  by  electricity ;  or,  more  correctly,  it  is  an 
apparatus  wherein  electrical  energy  is  converted  into  me- 
chanical energy.  Unscientifically  defined,  it  is  one  of 
those  contrivances  which  appear  especially  to  have  been 
"for  man's  illusion  given."  It  has  caused  more  waste 
of  time,  more  useless  expenditure  of  money,  and  more 
heart-breaking  disappointments,  than  perhaps  any  other 
single  device  evolved  by  human  ingenuity.  From  the  very 
beginning,  it  has  exercised  an  irresistible  fascination  upon 
the  inventive  mind.  Its  possibilities  were  within  easy 
range  of  speculation,  from  the  outset.  That  it  might 
prove  a  substitute  for  the  steam-engine  with  its  heat  and 
smoke  and  danger  and  waste,  was  apparent.  A  few 
pounds  of  zinc,  noiselessly  consumed  in  the  battery,  would 
replace  the  explosive  boiler  dependent  upon  coal  only  to 
be  obtained  at  an  expense  increasing  as  the  supply  dimin- 
ished. The  tremendous  power  exerted  could  be  arrested, 
or  set  in  operation,  or  governed,  by  the  touch  of  a  child's 
finger.  It  could  be  conveyed  anywhere  and  everywhere, 
by  slender  wires,  to  objects  moving  as  well  as  stationary. 
It  could  drive  ships  and  locomotives,  and  all  the  machinery 
of  the  world.  In  brief,  as  the  power  of  falling  water  and 
of  the  moving  wind  had  supplanted  the  power  of  the  horse, 


ELECTEO-MOTOES.  153 

and  as  the  power  of  steam  in  turn  had  taken  the  place  of 
the  power  of  wind  and  water,  so  in  the  future  electricity 
would  do  the  work  of  steam.  All  this  was  as  plain  fifty 
years  ago  as  it  is  now.  It  is  far  from  being  a  delusion  : 
we  are  advancing  toward  its  realization  with  wonderful 
rapidity.  But  in  that  it  all  could  be  accomplished  by  the 
ways  and  means  of  the  third  and  fourth  decades  of  this 
century,  lay  the  error, — one  that  still  is  being  repeated, 
and  always  with  the  same  result,  —  loss  and  disappoint- 
ment. 

The  idea  of  a  machine  to  be  driven  by  electrical  power, 
and  capable  of  doing  useful  work,  followed  as  a  necessary 
consequence  upon  the  discovery  of  the  immense  attractive 
strength  of  the  electro-magnet.  Why,  it  was  argued, 
should  that  ignis  fatuus,  that  other  form  of  the  perpetual 
motion, — the  cutting-off  the  magnetism  of  a  permanent 
magnet  by  a  screen  of  something  to  be  interposed  by  the 
attraction  of  the  magnet  itself,  be  further  sought,  when 
the  electro-magnet  could  be  made  to  exert  its  huge 
strength,  or  be  rendered  powerless,  instantly  and  at  will, 
by  the  mere  contact  or  separation  of  the  ends  of  a  wire? 
"When  the  current  is  established  in  its  coil,  the  electro- 
magnet attracts  its  armature :  when  the  current  is  inter- 
rupted, the  armature  is  released  to  fall  back  into  its 
original  position,  or  to  lie  retracted  by  a  simple  spring. 
If  the  current  is  established  and  broken  alternately,  then 
the  armature  will  reciprocate  to  and  fro  like  the  piston  of 
a  steam-engine  ;  and,  like  the  piston,  it  may  operate  other 
mechanism  to  produce  rotaiy  or  any  other  form  of  motion. 

The  lazy  boy  who  was  set  to  work  the  valve  of  the  old 
engine,  in  order  to  let  in  steam  at  the  proper  time  to  move 
the  piston  in  the  cylinder  to  and  fro,  found  out  that  if  he 
attached  the  string  wherewith  he  pulled  open  the  valve, 
to  the  moving  machine,  the  latter  would  itself  admit  the 


154  THE  AGE  OF  ELECTRICITY. 

steam  at  the  right  intervals.  The  same  idea,  applied  to 
the  electro-magnet  and  its  armature,  made  the  motor 
automatic.  When  the  armature  is  attracted,  in  moving 
it  may  draw  apart  the  ends  of  the  wire  whereby  the  cur- 
rent is  led  to  the  magnet.  Then  the  magnet  will  release 
the  armature.  In  falling  back,  the  armature  again  brings 
the  ends  of  the  conductor  into  contact.  Then  it  will  be 
once  more  attracted.  And  thus  it  will  go  on  vibrating  to 
and  fro  before  the  pole  of  the  magnet,  as  long  as  the 
supply  of  current  is  kept  up. 

This  idea  came  to  inventors  all  over  the  civilized  world, 
at  about  the  same  time.  Electro-motors  varying  only  in 
details  of  construction  appeared  simultaneously  in  Eng- 
land, France,  Germany,  Italy,  and  the  United  States. 
Modern  research  has  shown  that  probably  the  first  ma- 
chine was  constructed  by  the  Abbe"  Salvatore  dal  Negro, 
professor  in  the  University  of  Padua,  in  1830  ;  although 
the  earliest  published  description  of  it  appeared  some  two 
or  three  years  later.  Dal  Negro  suspended  a  permanent 
magnet  between  the  poles  of  a  horseshoe-shaped  electro- 
magnet, in  the  coils  of  which  the  current  was  alternately 
reversed,  so  that  the  end  of  the  suspended  magnet  was 
first  attracted  and  then  repelled  from  side  to  side.  By 
means  of  a  simple  mechanism  the  swinging  magnet  turned 
a  wheel  slowly  and  with  little  power. 

Professor  Joseph  Henry,  in  this  country,  constructed 
an  exceedingly  powerful  electro-magnet,  capable  of  lifting- 
six  or  seven  hundred  pounds  with  a  pint  or  two  of  liquid 
and  a  battery  of  corresponding  size  ;  nor  did  he  desist 
until,  a  short  time  after,  he  lifted  thousands  of  pounds  by 
a  battery  of  larger  size,  but  still' very  small.  Subsequently 
Henry  constructed  an  electro-magnetic  engine,  having 
a  beam  suspended  in  the  centre  which  performed  regular 
vibrations  in  the  manner  of  the  beam  of  a  steam-engine. 


ELECTRO-MO  TORS 


155 


Bourbouze  in  France  devised  the  remarkable  machine 
which  is  represented  in  Fig.  78.  Here  two  electro- 
magnet coils  successively  attract  two  pieces  of  soft  iron ; 
and  each  of  these,  placed  at  the  extremities  of  an  oscil- 
lating beam,  is  drawn  into  the  interior  of  the  coil.  When 
the  current  passes  into  one  coil,  the  iron  armature,  being 
drawn  down,  causes  the  end  of  the  beam  to  which  it  is 


Fig.  78. 

attached  to  descend  :  when  the  current  passes  into  the 
other  coil,  the  other  end  of  the  beam  goes  down.  The 
beam  in  vibrating  turns  a  crank,  and  so  rotates  the  fly- 
wheel. The  battery  is  placed  in  the  base  of  the  machine, 
and  communicates  witli  a  special  piece  of  metal,  the  pur- 
pose of  which  is  to  interrupt  the  current  and  throw  it 
alternately  from  one  side  to  the  other.  This  arrangement 
is  carried  out  simply  by  means  of  two  small  bits  of  iron, 
separated  by  a  plate  of  ivory.  A  metallic  spring  rests 


156  THE  AGE  OF  ELECTRICITY. 

upon  the  iron  and  ivory  at  the  end  and  at  the  beginning 
of  its  course,  now  on  the  first  bit  of  iron,  then  on  the 
second,  and  so  alternating ;  and  thus  the  current  is  led 
first  into  one  coil,  and  then  into  the  other. 

In  all  mechanical  contrivances,  where  motion  is  rapidly 
reversed,  there  is  a  great  waste  of  power ;  this  because 
the  momentum  of  the  moving  part  must  be  overcome 
before  the  direction  of  motion  can  be  changed.  It  was 
soon  found  that  this  principle  applied  very  cogently  to 
reciprocating  electro-motors. 

The  first  rotary  electro-motor  was  described  in  "The 
Mechanics'  Magazine"  of  June,  1833.  The  apparatus 
consisted  of  a  bent  electro- magnet,  "an  arc  of  iron 
measuring  about  two-thirds  of  a  circle,  and  supposed  to 
be  armed  with  a  helix  of  wire,  and  connected  with  a 
galvanic  battery."  The  armature  was  solid,  and  upon  it 
were  fixed  permanent  magnets  built  of  steel  bars  ;  the 
poles  of  the  magnets  being  placed  so  that  they  would  move 
"  all  but  in  contact"  with  the  poles  of  the  arc  magnet. 
The  communication  is  anonymously  signed,  but  is  of  espe- 
cial interest  from  the  fact  that  the  writer  describes,  with 
great  clearness,  an  apparatus  which  embodies  every  thing 
that  is  essential  to  the  construction  of  electro-motors  of 
the  class  to  which  it  belongs,  and  includes  features  sub- 
sequently patented  over  and  over  again  as  original  with 
numerous  claimants  to  the  invention. 

In  the  fall  of  1835  the  Rev.  Mr.  McGawley  exhibited 
to  the  British  Association  a  motor  in  which  a  pendulum 
vibrated  between  two  electro-magnets,  the  poles  of  which 
were  alternately  reversed,  so  that  first  one  magnet  at- 
tracted and  the  other  repelled  the  pendulum,  and  vice 
versa.  This  created  considerable  scientific  interest,  and 
was  pronounced  the  "  best  attempt  yet  made,  of  the  many 
schemes  that  had  been  proposed  for  producing  motive 


EL  ECTR  O-MO  TOR  ft.  157 

power  by  the  electro-magnet."  McGawley's  invention, 
like  that  of  Dal  Negro  which  it  very  much  resembled,  is 
in  fact  of  little  value  as  an  electro-magnetic  engine  ;  but 
it  is  of  much  historical  importance  for  the  reason  that  it 
contained  the  first  automatic  circuit-breaker,  —  wires  dip- 
ping alternately  first  into  one  cup  of  mercury  and  then 
into  another.  This  was  subsequently  patented  in  the 
United  States  to  Professor  Page  of  Washington  ;  a  pro- 
ceeding difficult  to  understand,  in  view  of  the  fact  that 
Page  himself  had  written  to  Sir  David  Brewster,  —  the 
chairman  managing  a  relief-fund  for  McGawley's  heirs, 
—  conceding  in  explicit  terms  the  invention  to  McGawley. 
The  fortunes  of  Thomas  Davenport  with  his  electro- 
motor constitute  a  curious  chapter  in  the  history  of  the 
apparatus.  Davenport  was  a  country  blacksmith,  living 
in  Brandon,  Vt.  By  accident  he  became  possessed  of  one 
of  Henry's  magnets,  and  by  dint  of  hard  work  and  per- 
severance —  for  he  had  no  special  education  —  he  con- 
trived to  master  the  principles  involved.  This  was  in 
1833.  By  the  summer  of  1834  Davenport  had  invented 
his  rotary  motor,  which  he  subsequently  patented  in  this 
country  in  1837.  It  was  substantially  like  the  apparatus 
described  by  the  anonymous  writer  in  "The  Mechanics' 
Magazine"  of  1833;  except  that  the  armature  had  elec- 
tro-magnets instead  of  permanent  magnets,  and  the  field 
magnet  was  a  permanent  magnet  instead  of  an  electro- 
magnet, the  apparently  earlier  contrivance  being  to  this 
extent  reversed.  Subsequently  he  suppressed  permanent 
magnets  altogether,  and  used  electro-magnets  only,  both 
as  field  and  armature.  The  machine  worked  well.  It 
was  exhibited  in  Washington  before  the  President,  and 
subsequently  in  Saratoga,  whither  great  crowds  of  people 
flocked  to  see  it,  and  lost  their  heads  over  it.  So  did  the 
newspapers,  scientific  and  unscientific.  "  The  American 


158  THE  AGE  OF  ELECTRICITY. 

Journal  of  Science  and  Arts  "  concluded  that  the  "  power 
generated  by  electro-magnetism  may  be  indefinitely  pro- 
longed .  .  .  and  increased  beyond  any  limit  hitherto  at- 
tained." Davenport  thought  that  a  battery  "as  big  as 
a  barrel  "  would  drive  the  largest  machinery,  and  that 
' '  half  a  barrel  of  blue  vitriol  and  a  hogshead  or  two  of 
water  would  send  a  ship  from  New  York  to  Liverpool." 

The  American  people  seem  to  have  contented  them- 
selves with  purely  mental  speculation  as  to  the  future  of 
the  machine,  and  to  have  declined  pecuniary  investment. 
Consequently  Davenport  sent  the  apparatus  to  England. 
It  captivated  John  Bull  at  first  sight.  Abundant  funds 
were  subscribed  to  build  a  u  big  machine,"  — the  invari- 
able requirement,  since  time  immemorial,  of  the  investor 
in  new  inventions.  Accordingly  one  was  constructed  hav- 
ing four  huge  electro-magnets  aggregating  in  weight  some 
three  hundred  pounds.  A  battery  "  as  big  as  a  barrel" 
was  made  to  charge  it.  It  had  a  cast-iron  wheel  six  feet 
in  diameter,  and  weighing  six  hundred  pounds,  which 
revolved  at  seventy-five  turns  a  minute. 

Among  the  scientific  men  who  came  to  see  this  new 
wonder,  were  Wheatstone  (already  famous  for  his  inven- 
tions in  telegraphy),  Daniell  (equally  renowned  for  his 
invention  of  the  Daniell  battery),  and  Faraday,  then  in 
the  zenith  of  his  fame  as  a  discoverer.  Wheatstone 
praised  the  machine  in  glowing  terms ;  Daniell  waxed 
enthusiastic  over  it,  and  predicted  the  time  when  ships 
would  be  run  across  the  Atlantic  with  the  aid  of  a  few 
sheets  of  zinc  and  a  little  acid, — yea,  not  even  acid,  for 
the  waters  of  the  ocean  would  supply  its  place. 

Faraday  came  last  of  all.  He  looked  at  the  huge  wheel 
flying  around,  with  surprise ;  and  then  fixed  his  gaze  more 
intently  on  the  great  spark  which  was  given  off  every  time 
the  current  was  broken,  yielding  enough  light  to  illuminate 


ELECTRO-MOTORS.  159 

brightly  the  whole  room.  The  promoters  of  the  machine 
stood  silent,  expectantly  waiting  the  verdict  from  the  fore- 
most scientific  authority  in  the  land.  After  a  while,  Fara- 
day walked  to  the  nearest  corner,  and  picked  up  a  broom. 
Then  he  placed  the  handle  on  the  periphery  of  the  wheel, 
and  it  was  seen  that  under  a  slight  pressure  the  speed 
of  the  wheel  became  slower.  He  did  not  quite  stop  the 
motion,  but  simply  and  without  a  word  demonstrated  how 
easily  this  could  be  done.  Then  he  called  the  promoters 
aside  into  another  room,  and  gently  suggested  that  his 
opinion,  if  made  public,  would  greatly  injure  the  sale  of 
the  patent.  The  interested  parties  thought  it  wiser  not  to 
press  him  for  that  opinion,  and  he  left  without  giving  it. 
He  had  found,  as  others  did  later,  that  the  power  yielded 
was  wholly  inadequate  for  practical  use. 

After  this  Davenport  started  a  paper  in  New- York 
City,  called  "The  Electro-Magnet  and  Mechanics'  Intelli- 
gencer," the  first  number  of  which  appeared  on  Jan.  18, 
1840.  He  announced  it  as  the  first  paper  ever  printed  on 
a  press  propelled  by  electro-magnetism.  The  public  re- 
garded the  enterprise  rather  apathetically.  In  his  second 
issue,  Davenport  particularly  requested  "those  who  would 
wish  to  advance  the  cause  of  philanthropy  to  come  for- 
ward and  assist  us  in  our  experiment."  Perhaps  he  failed 
to  make  clear  the  connection  between  his  newspaper  and 
the  u  cause  of  philanthropy;"  or  perhaps  the  public, 
after  three  years  excitement  over  his  machine,  had  tired 
of  the  subject:  at  all  events,  the  paper  ceased  publica- 
tion, and  in  the  technical  journals  of  the  day  no  further 
record  of  Davenport's  motor  appears. 

One  of  the  best  of  the  early  forms  of  rotary  motor  was 
that  devised  in  France  by  M.  Froment,  which  is  represented 
in  Fig.  79.  Around  the  periphery  of  a  skeleton  drum  are 
arranged  eight  pieces  of  iron,  which  serve  as  armatures. 


160 


THE  AGE   OF  ELECTRICITY. 


In  the  frame  of  the  machine  are  fixed  six  couples  of  elec- 
tro-magnets. (The  two  upper  couples  are  omitted  in  the 
engraving.)  When  the  current  is  diverted  into  one  of 
these  coils,  one  of  the  armatures  is  attracted,  and  is 
moved  to  a  position  in  front  of  the  pole  of  the  magnet. 
The  wheel  is  so  turned  over  a  certain  distance.  As  soon, 


however,  as  the  armature  has  thus  placed  itself,  the  cur- 
rent is  thrown  from  the  first  coil  into  the  next  one,  which 
draws  the  armature  to  its  pole  in  turn.  As  all  six  electro- 
magnets act  in  this  way,  the  wheel  is  continuously  rotated. 
The  interest  aroused  by  the  exhibitions  made  by  Daven- 
port in  London  extended  over  all  Europe  ;  and  in  the  fall 
of  1838  Professor  Jacobi  was  invited  by  the  Emperor  of 


ELECTEO-MOTOES.  161 

Russia  to  conduct  experiments  on  a  large  scale,  with  the  ob- 
ject of  determining  the  practicability  of  the  electro-motor 
for  marine  propulsion.  Jacobi's  vessel  was  a  ten-oared 
shallop,  equipped  with  paddle-wheels,  to  which  rotary 
motion  was  communicated  by  an  electro-magnetic  engine. 
In  general  there  were  ten  or  twelve  persons  on  board  ;  and 
the  voyage,  which  was  made  on  the  River  Neva,  was  con- 
tinued for  entire  days.  The  difficulty  of  managing  the 
batteries,  and  the  imperfect  construction  of  the  engine, 
were  sources  of  frequent  interruption,  which  could  not  be 
well  remedied  on  the  spot.  After  these  difficulties  were 
in  some  degree  removed,  the  professor  gives,  as  a  result 
of  his  experiments,  that  a  battery  of  twenty  square  feet 
of  platinum  will  produce  a  power  equivalent  to  one  horse, 
but  he  hoped  to  be  able  to  obtain  the  same  power  with 
about  half  that  amount  of  battery  surface.  The  vessel 
went  at  the  rate  of  four  miles  per  hour,  which  is  certainly 
more  than  was  accomplished  by  the  first  little  boat  pro- 
pelled by  the  power  of  steam.  Jacobi's  boat  was  28  feet 
long  and  1\  feet  in  width,  and  drew  2f  feet  of  water. 
The  machine,  which  occupied  little  space,  was  worked  by 
a  battery  of  sixty-four  pairs  of  platinum  plates,  each  hav- 
ing thirty-six  square  inches  of  surface,  and  charged,  ac- 
cording to  the  plan  of  Grove,  with  nitric  and  sulphuric 
acid.  The  boat,  with  a  party  of  twelve  or  fourteen .  per- 
sons on  board,  went  against  the  stream  at  the  rate  of  three 
miles  per  hour.  This  experiment  was  tried  in  1839,  and 
shows  what  great  progress  had  been  made  in  the  period  of 
about  one  year ;  for  in  1838,  when  it  was  attempted  to 
propel  the  same  boat  by  the  same  machine,  a  battery  of 
about  five  times  the  size  was  required.  Jacobi's  batteries 
generated  so  much  gas,  that  the  fumes  seriously  discom- 
moded the  operators,  and -at  times  compelled  them  to 
abandon  their  experiments ;  and  even  the  spectators  on 


162  THE  AGE  OF  ELECTRICITY. 

the  banks  were  forced  to  retire  when  the  wind  blew  in 
their  direction. 

Jacobi  wrote  a  letter,  describing  his  results,  to  Faraday  ; 
and  this,  being  published,  elicited  one  from  Professor 
Forbes  of  King's  College,  Aberdeen,  in  which  for  the 
first  time  the  labors  of  Mr.  Robert  Davidson  of  that  place 
were  brought  to  light.  Davidson's  most  remarkable  per- 
formance was  his  locomotive.  He  used  two  batteries, 
arranged  at  each  end  of  his  carriage,  which  energized  a 
number  of  large  electro-magnets.  On  the  wheel-axles 
were  large  cylinders,  on  the  peripheries  of  which  were 
fastened  masses  of  iron.  These  masses  were  attracted 
by  the  magnets  ;  and  in  this  way  the  cylinders  were  re- 
volved, so  rotating  the  wheels.  The  carriage,  Davidson 
claimed,  was  once  tested  on  the  Edinburgh  and  Glasgow 
Railway,  where  it  ran  at  the  rate  of  about  four  miles  per 
hour.  It  was  sixteen  feet  in  breadth,  and  weighed  some 
five  tons.  This  report  has  always,  as  the  newspapers  say, 
"lacked  confirmation." 

Davidson's  experiments  had,  however,  gone  far  to  show 
the  disadvantages  of  carrying  the  batteries  on  the  locomo- 
tive. In  the  fall  of  1845,  "The  Mechanics'  Magazine  " 
published  a  letter  signed  "  J.  M.,"  which  contained  this 
significant  suggestion :  — 

"  Now,  suppose  we  have  a  railway  ten  miles  long,  and 
that  at  one  terminus  is  placed  an  enormous  stationary  gal- 
vanic battery,  might  we  not  make  the  rails  themselves  the 
conducting  lines  of  the  battery?  and,  the  wheels  being  so 
arranged  as  to  break  the  connection  where  required,  a 
rotating  magnet  might  revolve  by  the  electro-magnetism 
thus  communicated.  .  .  .  Perhaps  some  fertile  brain  may 
take  the  hint,  and  bring  forth  soon  the  4  electric  rail- 
way/ " 

A  fertile  brain  on  this  side  of  the  Atlantic  was  already 


ELECTRO-MOTORS.  163 

working  on  this  idea ;  and  it  was  carried  into  practical 
execution  by  Mr.  John  B.  Lilly,  who  in  1846  exhibited  in 
Pittsburg,  Penn.,  a  model  which  was  driven  by  a  current 
passing  up  one  rail  and  down  another,  and  through  the 
magnets  on  the  car.  "Heretofore,"  says  "The  Pitts- 
burgh Journal"  of  the  time,  "the  propelling  power  has 
been  used  on  the  car  itself :  in  this  instance,  however,  the 
power  is  in  the  rails  ;  and  an  engineer  might  remain  in 
one  town ,  and  with  his  battery  send  a  locomotive  and  train 
to  any  distance  required." 

Five  years  later  Professor  Page  of  Washington  made  a 
trial  trip,  with  an  electro-magnetic  locomotive,  between 
Bladensburg  and  Washington.  It  was  claimed  to  be  of 
sixteen  horse  power,  and  was  provided  with  a  hundred 
cells  of  Grove's  nitric-acid  battery,  each  having  platinum 
plates  eleven  inches  square.  It  is  stated  that  the  progress 
of  the  locomotive  was  at  first  so  slow  that  a  boy  was  en- 
abled to  keep  pace  with  it  for  several  hundred  feet ;  but 
the  speed  was  soon  increased,  and  Bladensburg,  five  miles 
and  a  quarter  distant,  was  reached  in  thirt}'-nine  minutes. 
When  within  two  miles  of  that  place,  the  power  of  the 
battery  being  fully  up,  the  locomotive  began  to  run  on 
nearly  a  level  plane,  at  the  rate  of  nineteen  miles  an  hour. 
This  velocity  was  kept  up  for  about  a  mile,  when  some  of 
the  battery  cells  cracked,  and  their  liquids  became  inter- 
mixed. Considerable  time  was  lost  in  stoppages ;  but 
the  return  trip  was  safely  accomplished,  the  entire  running 
time  being  one  minute  less  than  two  hours.  It  was  found 
on  subsequent  trials,  that  the  least  jolt,  such  as  that  caused 
by  the  end  of  a  rail  a  little  above  the  level,  threw  the  bat- 
teries out  of  working  order,  and  the  result  was  a  halt. 
This  defect,  it  is  said,  could  not  be  overcome  ;  and  Pro- 
fessor Page  reluctantly  abandoned  his  endeavors. 

In  the  same  year  Thomas  Hall  of  Boston  constructed 


164  THE  AGE  OF  ELECTRICITY. 

a  small  locomotive  which  ran  on  a  track  some  twenty  feet 
long,  and  took  the  current  from  the  rails,  the  wheels  being 
insulated.  It  has  been  claimed  for  Hall,  that  he  utilized 
not  only  a  battery  to  supply  his  current,  but  also  a  dy- 
namo-electric machine. 

Some  twenty-one  years  had  now  elapsed  since  the  first 
electro-motor  —  Dal  Negro's  mere  toy  —  had  been  pro- 
duced. In  that  period  both  forms  of  the  machine,  beam 
and  rotary,  had  been  invented.  It  had  been  applied  to 
the  propulsion  of  vessels  and  of  locomotives  ;  the  last 
being  operated  by  batteries  carried  by  themselves,  as  is 
the  steam-boiler  of  the  modern  railway-engine,  and  by 
batteries  at  a  distance,  which  transmitted  their  current  to 
the  motor  through  the  rails.  About  all  the  principal  adap- 
tations of  the  electric  engine  had  been  made.  It  had 
claimed  the  attention  and  labors  of  the  most  noted  scien- 
tists of  the  world.  It  had  been  backed  by  an  emperor  of 
unlimited  power,  and  capitalists  representing  unbounded 
wealth  had  endeavored  again  and  again  to  make  it  the 
basis  of  successful  enterprise.  And  yet  when  the  success 
of  the  electric  telegraph,  which  had  seemed  far  the  greater 
impracticability,  aroused  the  wonder  and  admiration  of 
the  world,  the  electric  motor  worked  usefully  for  no  man. 
What  was  the  reason? 

As  we  have  seen,  the  inventors  of  the  early  machines 
found  no  trouble  in  making  them  go.  The  beams  vibrated, 
or  the  wheels  spun  around,  fast  enough  to  make  people 
with  vague  ideas  about  speed  and  power  believe  that 
almost  limitless  energy  could  be  got  out  of  a  pint  pot. 
The  early  inventors,  and  those  who  promoted  their  pro- 
jects, are  not  the  only  persons  chargeable  with  this  delu- 
sion. It  exists  yet,  and  crops  out  occasionally.  In  1871 
a  New- Jersey  discoverer  asserted  that  he  could  make  a 
fifty-pound  electro-magnet  sustain  a  weight  of  one  hundred 


ELECTRO-MOTORS.  165 

and  twenty  tons  with  a  battery  of  four  Daniell's  cells, 
and  drive  a  five-hundrecl-horse-power  engine  by  the  same 
means,  at  an  expense  of  but  twenty  cents  a  day.  An 
electro-magnetic  engine  company  —  as  usual  —  was  organ- 
ized ;  capital,  three  millions.  The  engine  was  to  be  ex- 
hibited on  the  4th  of  July  —  year  indefinite.  Also — as 
usual  —  there  was  an  element  of  mystery  introduced,  in 
the  assertion  that  the  battery  was  merely  a  connecting 
link  between  the  machine  and  some  storehouse  of  mag- 
netic energy,  and  therefore,  that,  while  the  battery  was 
apparently  the  source  of  power,  it  really  was  not ;  bearing 
a  relation  thereto,  similar  to  that  of  a  percussion-cap  which 
fires  the  charge  which  impels  the  cannon-shot.  Public 
interest  in  this  great  discovery — or,  rather,  that  section 
of  the  public  interest  which  is  ignorant  enough  to  give 
such  discoveries  consideration  — was  transferred  two  years 
later  to  the  Keely  motor ;  which  was  obviously  of  much 
greater  importance,  because  it  did  not  even  require  the 
pint  pot  wherefrom  to  obtain  limitless  power. 

The  great  vicissitude  which  invariably  came  to  promoters 
of  electro- magnetic  engines  driven  by  batteries,  was  the 
discovery  that  they  do  not  pay  ;  and  no  amount  of  glowing 
anticipations  in  prospectuses  could  prevent  stockholders 
becoming  painfully  aware  of  this,  in  the  end.  It  is  much 
cheaper  —  besides  far  easier  —  to  take  the  mere  fuel  used 
in  extracting  the  zinc  from  its  ore,  and  burn  it  under  a 
steam-boiler,  to  drive  a  steam-engine,  and  so  obtain  power 
in  that  way,  than  to  go  through  the  roundabout  process 
of  extracting  the  zinc,  consuming  it  in  a  galvanic  cell, 
and  so  generating  a  current  wherewith  to  drive  a  motor. 
Zinc,  as  we  have  already  pointed  out,  yields  about  one- 
seventh  the  energy  of  coal,  and  costs  about  twenty  times 
as  much.  Merely  comparing  the  energies  derivable  from 
zinc  and  coal,  a  steam-engine  should  be  about  a  hundred 


166  THE  AGE  OF  ELECTRICITY. 

and  forty  times  more  economical  than  an  electro-motoi 
driven  by  a  battery.  But  the  best  steam-engine  and  boiler 
can  utilize  no  more  than  about  two-ninths  of  the  energy 
of  the  burning  coal ;  all  the  rest  being  wasted.  This 
reduces  the  difference  :  it  is  "  not  so  deep  as  a  well,  nor 
so  wide  as  a  church-door,  but  'tis  enough,"  since  it  leaves 
the  motor  some  thirty  times  as  expensive  in  the  produc- 
tion of  power  as  the  steam-engine.  The  efficiency  of 
the  motor  has  no  part  in  this  question.  The  battery  is  the 
hopelessly  inefficient  part  of  the  system ;  and  it  will 
remain  so,  no  matter  how  much  the  motor  itself  may 
hereafter  be  improved.  According  to  Professor  Joule, 
the  cost  of  zinc  expended  in  the  Daniell  battery,  to  main- 
tain one  horse  power  for  twenty- four  hours,  would  be 
$6.25  ;  in  an  ordinary  steam-engine,  the  cost  of  the  same 
power  for  the  same  period  would  be  about  twenty-one 
cents.  From  a  "business"  point  of  view,  no  further 
argument  is  necessary  to  show  why  electro-motors  driven 
from  galvanic  batteries,  as  were  all  the  early  machines, 
could  find  no  place  in  the  world's  work. 

While  one  set  of  investigators  and  inventors  were  study- 
ing how  to  convert  electricity  into  mechanical  power, 
another  set,  almost  simultaneously,  were  endeavoring  to 
convert  mechanical  power  into  electricity.  The  researches 
of  these  last  culminated  in  the  modern  dynamo  electric 
machine.  Now,  the  machines  which  generate  electricity 
from  motion  bear  a  strong  resemblance,  in  point  of  gen- 
eral construction,  to  those  which  generate  motion  from 
electricity.  Let  us  repeat  one  illustration  already  given, 
to  show  this. 

Fig.  80  we  have  already  described  as  a  hollow  coil  of 
wire,  the  ends  of  which  are  connected  to  a  galvanometer, 
which  shows  by  the  movement  of  its  needle  whenever  a 
current  circulates  in  that  coil.  Into  that  coil  we  insert 


ELECTRO-MOTORS. 


167 


a  smaller  coil,  the  ends  of  which  are  connected  to  a  bat- 
tery. We  have  seen,  that,  when  the  small  coil  is  moved 
to  and  fro  inside  the  large  one,  then  the  galvanometer  will 
show  that  a  current  is  being  generated  in  the  large  coil. 
We  are  thus  converting  the  energy  of  the  motion  given 
to  the  small  coil,  into  electricity. 

Now,  let  us  simply  reverse  the  arrangement  of  the 
battery,  connecting  it  to  the  ends  of  the  large  coil,  remov- 
ing the  galvanometer.  Let  us  also  join  the  ends  of  the 


Fig.  80. 

small  coil  together.  Then  when  the  current  passes  through 
the  large  coil,  on  holding  the  smaller  coil  in  -the  position 
shown  in  the  engraving  we  shall  feel  the  large  coil  pull 
the  smaller  one  into  it,  release  it  when  the  current  is 
broken,  and,  if  we  draw  out  the  small  coil,  on  re-estab- 
lishing the  current  it  will  be  pulled  back  again,  so  moving 
to  and  fro.  Here  the  electricity  circulating  in  the  large 
coil  is  converted  into  motion. 

The  same  thing  can  be  done  with  the  arrangement  rep- 
resented in  Fig.  81.     We  have  seen,  that,  when  the  per- 


168 


THE  AGE  OF  ELECTRICITY. 


manent  magnet  is  moved  into  and  out  of  the  coil,  a  current 
is  caused  in  the  latter.  If  the  current  be  sent  directly 
through  the  coil  in  one  direction,  the  magnet  will  be  drawn 
in :  if  in  the  opposite  direction,  it  will  not  be  attracted, 
Or  if,  instead  of  the  magnet,  we  use  simply  a  piece  of  soft 
iron,  then,  whenever  the  current  is  established,  the  iron 
will  be  drawn  inward,  and  when  broken  it  will  be  free  to 
be  moved  out,  —  as  by  a  spring,  for  example. 

If  the  foregoing  be  compared 
with  the  engraving  of  Bourbouze's 
electro-magnetic  engine  on  p.  155, 
it  will  be  seen  that  that  apparatus 
depends  exactly  on  the  opeiation 
last  described.  An  electro-motor 
is  in  fact  a  dynamo  or  magneto 
electric  machine  reversed.  If  a 
dynamo  is  rotated  by  mechanical 
power,  it  will  produce  an  electric 
current.  If  an  electric  current  be 
conducted  into  a  dynamo,  its  arma- 
ture will  be  rotated.  Good  dynamo 
machines,  in  fact,  make  the  best 
motors  ;  and  the  latter,  like  the  dynamos,  resolve  them- 
selves, as  we  have  seen,  into  two  types,  distinguished  by 
the  production  of  alternating  and  continuous  currents  in 
the  armature.  There  are,  however,  certain  functional 
differences  between  motors  and  dynamos,  which  require 
to  be  met  in  different  ways,  and  particularly  in  the  pro- 
portioning of  the  parts,  and  the  relation  of  the  field  and 
armature  systems.  These  need  not  be  discussed  in  detail 
here. 

As  the  dynamo  machine  became  more  and  more  efficient, 
it  became  evident  that  here  was  a  means  of  producing 
electricity  which  could  be  used  to  drive  a  motor,  as  well 


Fig.  81. 


ELECTEO-MOTOES.  169 

as  supply  an  electric  lamp,  and  which  would  depend  for 
economy  not  upon  zinc,  but  upon  coal.  And  thus  the 
modern  system  of  electro-motors,  and  the  transmission  of 
power  thereto  at  a  distance,  came  into  existence :  and 
of  this  the  essentials  are  a  heat  engine  —  steam  or  gas  — 
to  drive  a  dynamo,  which  supplies  the  current  to  a  second 
dynamo ;  and  this  last  converts  the  energy  of  the  elec- 
tricity, so  supplied,  into  mechanical  motion  and  work. 

We  know  that  the  revolution  of  the  armature  of  a 
dynamo  produces  a  current ;  and  that  in  large  dynamos, 
producing  a  very  strong  current,  it  is  necessary  to  use 
powerful  engines  to  turn  the  armature.  But  if  the  circuit 
in  the  armature  is  broken,  no  such  power  is  required.  It 
is  only  when  the  current  is  being  yielded,  that  hard  work 
must  be  done  to  rotate  the  armature  ;  and  we  therefore 
say  that  this  work  has  its  equivalent  in  the  electric  current 
which  flows  and  in  the  heat  which  is  caused  in  the  circuit, 
which  is  rendered  visible  by  the  incandescence  of,  for  ex- 
ample, an  electric  lamp  placed  therein.  Now,  whether  the 
armature  of  a  dynamo  be  rotated  directly  by  an  engine,  or 
whether  it  be  rotated  by  a  current  sent  into  the  machine, 
a  new  current  will  be  produced.  If  the  dynamo  be  turned 
by  the  engine,  this  current  will  of  course  be  the  only  one 
in  the  circuit ;  but  if  there  is  already  a  current  existing 
there,  as  when  the  dynamo  is  driven  by  electricity,  then 
the  new  current  will  be  in  the  opposite  direction  to  the 
original  one,  and  tend  to  diminish  the  latter.  This  makes 
complications  ;  and  the  result,  among  other  things,  is  a 
quantity  of  mathematical  calculation  which,  if  printed 
here,  might  perhaps  make  the  non-professional  reader 
shut  up  this  book  in  despair. 

It  will  suffice,  therefore,  to  say  briefly,  that,  when  the 
speed  of  the  electro-motor  is  increased,  this  back  current 
is  also  increased.  If  the  motor  be  loaded  so  as  to  do 


170  THE  AGE  OF  ELECTRICITY. 

work  by  moving  slowly  against  considerable  forces,  then 
the  back  current  will  be  small,  and  only  a  portion  of  the 
energy  of  the  current  will  be  turned  into  useful  work.  If, 
on  the  other  hand,  it  be  run  rapidly  so  as  to  make  con- 
siderable back  current,  it  will  utilize  a  larger  proportion  of 
the  energy  of  the  direct  current,  but  can  only  be  run  fast 
enough  to  do  this  if  its  load  be  very  light.  When  a  motor 
is  desired  to  do  its  work  at  the  quickest  possible  rate, 
it  is  best  operated  at  such  a  speed  that  the  supply  current 
is  reduced  to  half  its  strength ;  but  when  speed  is  not 
necessary,  a  greater  economic  efficiency  is  attainable  by 
letting  the  machine  do  lighter  work,  and  run  faster,  so 
that  the  back  current  is  nearly  equal  to  the  original  current, 
which  is  thereby  reduced  to  a  small  fraction  of  its  strength. 
A  Siemens  dynamo-electric  machine  used  as  a  motor  can 
attain  an  efficiency  of  over  eighty-five  per  cent.  A  good 
dynamo  can  turn  eighty-five  per  cent  of  the  mechanical 
power  it  receives,  into  the  energy  of  the  electric  current ; 
and  the  electro-motor  can  convert  back  eighty-five  per  cent 
of  the  current  energy  (or  seventy-two  per  cent  of  the  ori- 
ginal power)  into  work,  losses  in  the  conductor  and  from 
leakage  being  neglected. 

The  simplest  form  of  electro-motor  is  that  used  on 
electric  bells.  This  consists  of  an  electro-magnet  which 
moves  a  hammer  backward  and  forward,  alternately  attract- 
ing and  releasing  it.  In  Fig.  82,  E  is  the  electro-magnet, 
and  C  the  hammer.  By  touching  the  push-button  P, 
which  is  also  shown  enlarged  in  section,  the  circuit  from 
the  battery  L  is  completed,  and  a  current  flows  along  the 
line  and  around  the  coils  of  the  electro-magnet,  which 
attracts  a  small  piece  of  soft  iron  attached  to  the  lever  $, 
which  terminates  in  the  hammer  C.  The  lever  is  itself 
included  in  the  circuit,  the  current  entering  it  below  and 
quitting  it  by  a  contact-breaker  A,  consisting  of  a  spring 


ELECTRO-MOTORS. 


171 


tipped  with  platinum,  resting  against  the  platinum  tip  of 
a  screw  from  which  a  return  wire  passes  back  to  the  bat- 
tery. As  soon  as  the  lever  S  is  attracted  forward,  the 
circuit  is  broken  at  A  by  the  spring  moving  away  from 
contact  with  the  screw :  hence  the  current  stops,  and  the 
electro-magnet  ceases  to  attract  the  armature.  The  lever 
and  hammer  therefore  fall  back  again,  establishing  con- 
tact at  A,  whereupon  the  hammer  is  once  more  attracted 
forward,  and  so  on. 


Fig.  82. 

The  most  important  modern  application  of  electro- 
motors is  to  the  driving  of  locomotives.  The  credit  of 
the  first  successful  electrical  railway  is  due  to  Dr.  Werner 
Siemens,  who  built  in  Berlin,  in  1879,  a  narrow-gauge  line, 
laid  down  in  a  circle  some  nine  hundred  yards  in  length. 
A  train  of  three  or  four  carriages  was  placed  upon  it ; 
and  on  the  first  carriage  a  dynamo-electric  machine  was 
fixed  to  the  axle  of  one  pair  of  wheels,  in  such  a  manner 
as  to  rotate  the  wheels  when  the  armature  of  the  machine 
was  rotated  by  the  passage  of  a  current  through  its  coils. 


172 


THE  AGE  OF  ELECTRICITY. 


The  rails  were  laid  upon  wooden  sleepers,  which,  even  in 
wet  weather,  insulated  the  rails  very  well  for  this  length  of 
line.  A  third  rail  ran  between  the  other  two,  and  it  was  by 
this  central  conductor  that  the  current  was  led  from  the 
generating-machine  placed  at  one  terminus  of  the  line. 
The  current  was  drawn  from  this  rail  to  the  armature  of  the 
machine  on  the  locomotive,  by  means  of  a  brush  of  cop- 
per wires ;  and  after  traversing  the  coils  of  the  armature, 
it  was  led  to  the  axle  of  the  driving-wheels,  which  was 
insulated  from  the  body  of  the  car,  and  thence  by  the 
driving-wheels  to  the  outer  rails,  and  by  them  back  to 

the  dynamo  ma- 
chine at  the  termi- 
nus. Fig.  83  repre- 
sents a  section 
through  the  loco- 
motive, showing 
the  dynamo  -  elec- 
tric machine  5, 
and  the  central  rail 
JV,  with  the  metal 
brush  for  abducting 
the  current. 

Between  twenty  and  thirty  persons  could  be  accom- 
modated on  the  train  at  a  time,  including  the  conductor, 
who  rode  on  the  first  carriage  ;  and  during  the  course  of 
the  summer  no  fewer  than  a  hundred  thousand  were  con- 
veyed over  the  line  at  a  speed  of  from  fifteen  to  twenty 
miles  an  hour.  Crowded  trains  left  the  stations  every 
five  or  ten  minutes,  and  a  considerable  sum  was  earned 
in  this  way  for  the  benefit  of  charitable  institutions. 
The  locomotive  was  capable  of  exerting  five  horse-power  ; 
and  instead  of  being  fitted  with  a  steam  valve  like  a 
locomotive  to  start  or  stop  it,  it  was  simply  provided  with 


Fig.  83. 


ELECTRO-MOTORS.  173 

a  commutator  for  closing  or  opening  the  circuit  of  the 
current. 

On  the  Siemens  railway  at  the  Paris  exhibition  of  Sep- 
tember, 1881,  a  distance  of  over  sixteen  hundred  feet  was 
traversed  in  a  minute,  which  is  at  the  rate  of  nearly 
twenty  miles  per  hour. 

In  this  country,  electric  railways  have  in  many  locali- 
ties replaced  ordinary  street-railway  systems  depending 
on  horses  and  dummy  engines.  At  South  Bend,  Ind., 
for  example,  two  twenty-horse-power  dynamos  are  driven 
by  a  water-wheel,  and  supply  current  to  one  ten-horse- 
power and  three  five-horse-power  motors.  The  track  is 
laid  with  the  ordinary  flat  rail,  the  rails  being  connected 
by  copper  plates.  The  other  part  of  the  circuit  consists 
of  a  copper  wire  suspended  above  the  track.  From  the 
under  side  of  this  wire  hangs  a  carriage  fastened  to  a 
flexible  cable,  passing  to  the  inside  of  the  car,  where  it 
is  in  connection  with  the  switches,  the  motor,  etc.  When 
full  current  is  turned  on,  the  maximum  speed  of  eight 
miles  per  hour  is  attained,  this  being  the  highest  rate  of 
travel  allowable  in  the  city  limits.  An  electric  railway 
was  constructed  in  the  fall  of  1885  at  the  New-Orleans 
Exposition.  Others  are  in  successful  operation  in  Balti- 
more, Minneapolis,  Montgomery  (Ala.)  ;  and  there  are 
probably  few  large  cities  in  the  country  in  which  some 
system  of  electric  railway  has  not  been  projected.  At 
the  date  of  writing  (1886),  experiments  have  for  some 
time  been  in  progress  with  the  object  of  substituting  elec- 
tric engines  for  the  steam-engines  on  the  elevated-railway 
lines  in  the  city  of  New  York.  On  the  Ninth-avenue 
road,  arrangements  have  been  made  to  employ  the  form 
of  electric  locomotive  devised  by  Mr.  Leo  Daft.  The 
total  weight  of  the  machine  as  constructed  is  8f  tons. 
The  current  is  taken  from  the  rails,  which  are  insulated, 


174  THE  AGE  OF  ELECTEICITY. 

and  is  supplied  by  dynamos  situated  at  a  main  station. 
A  third  rail  between  the  track  rails  is  employed  for  the 
return  current,  and  contact  is  made  with  this  by  means  of 
a  wheel  which  can  be  moved  into  or  out  of  position.  The 
maximum  gradient  of  the  road  is  one  of  a  hundred  and 
five  feet  to  the  mile.  This  has  been  surmounted  with 
ease,  with  fairly  well  loaded  trains ;  and  an  average 
speed  of  twenty  miles  per  hour  has  been  attained.  The 
latest,  as  well  as  the  most  efficient  electro-locomotive,  is 
that  devised  by  Mr.  F.  J.  Sprague.  This,  also,  at  the 
present  time,  is  being  experimented  upon  on  the  elevated 
railways  of  New- York  City.  To  describe  the  construc- 
tion of  Mr.  Sprague's  apparatus,  would  necessitate  much 
technical  detail  not  suited  to  these  pages  ;  but  the  prac- 
tical results  which  he  has  attained,  especially  in  control  of 
speed,  prevention  of  loss  of  power,  and  facility  of  stopping 
and  starting,  renders  his  motor  a  decided  and  very  meri- 
torious advance  in  electric  propulsion. 

It  is  impossible  to  fix  a  limit  to  the  possible  speed  of 
electric  locomotives  ;  but  it  is  not  improbable  that  eventu- 
ally it  will  be  found  practicable  to  drive  them  at  much 
higher  velocities  than  the  steam-locomotive  has  ever  at- 
tained. The  advantages  of  electricity  over  steam  for 
railway  propulsion  are  so  great  as  to  render  the  former 
almost  an  ideal  prime  motor.  The  locomotive  itself  is 
virtually  done  away  with,  for  in  many  cases  the  electric 
motor  can  be  placed  under  the  car.  As  regards  economy, 
it  has  recently  been  pointed  out  that  "  the  evaporation  of 
pounds  of  water  to  each  pound  of  coal  to  make  steam 
in  locomotive-boilers  does  not  average  over  3J  pounds  of 
water,  using  the  best  grades  of  bituminous  coal ;  while 
with  stationary  boilers,  set  to  burn  coal-screenings  for 
fuel,  an  evaporation  of  nine  pounds  of  water  to  one 
pound  of  fuel  is  made,  and  the  reduction  in  cost  of  fuel 


ELECTRO-MOTORS.  175 

is  from  one-third  to  one-half."  The  cost,  therefore,  of 
making  the  electric  power,  is  already  greatly  less  than 
that  of  generating  steam-power  in  moving  locomotives  : 
and  when  electricity  comes  to  be  supplied,  as  it  eventually 
will  be,  like  gas  and  water,  from  great  central  generating 
stations,  to  be  used  for  all  purposes,  the  expense  of  its 
production  will  without  doubt  be  still  further  lessened. 
Add  to  the  above  advantages,  freedom  from  smoke  and 
sparks,  noiseless  machinery  and  motion,  and  absolute  con- 
trol by  the  mere  pressure  of  a  finger,  and  one  may  predict 
with  every  certainty  that  the  electric  steed  will  replace  the 
steam  horse,  as  certainly  as  the  latter  did  the  horse  of 
flesh  and  blood. 

Electric  power  is  already  sold  from  central  stations,  in 
many  places,  just  as  steam-power  is  sold,  with  profit  to 
both  seller  and  buyer.  The  price  at  present  is  about  the 
same  as  that  for  steam  for  small  powers.  In  Boston, 
steam  is  generated  from  coal-screenings,  to  drive  the 
engine  which  actuates  the  dynamos ;  and  the  power  is 
transmitted  all  over  the  city,  being  used  for  running  all 
kinds  of  machinery,  including  sewing-machines,  ventilator- 
fans,  printing-presses,  elevators,  etc. 

It  appears  that  ordinarily  the  loss  in  the  process  of  con- 
version of  power  into  electricity,  and  transmitting  power 
from  the  dynamo  to  the  receiver,  amounts  to  from  forty 
to  fifty  per  cent.  "Electrical  transmission,"  says  a 
recent  writer,  "has  the  unparalleled  advantage  of  being 
superior  to  the  obstacle  presented  by  distance.  Then, 
again,  it  operates  its  miracles  in  perfect  silence  and 
repose.  No  force  appears  in  the  wire,  such  as  appears  in 
shafting,  in  pipes  with  compressed  air  or  water,  in  endless 
chains  or  belts  ;  and  in  case  of  powerful  currents,  insula- 
tion is  easy.  The  conductor  can  be  bent  or  shifted  in  any 
way  while  transmitting  many  horse-power ;  provided,  of 


176  THE  AGE   OF  ELECTRICITY. 

course,  its  continuity  be  not  interrupted.  It  can  be  car- 
ried round  the  sharpest  corners,  through  the  most  private 
rooms,  into  places  where  no  other  transmitter  or  power 
could  possibly  be  taken.  There  is  nothing  to  burst  or 
give  away.  In  short,  such  a  method  of  transmission  is 
the  acme  of  dynamical  science." 

Electro-motors  have  been  ingeniously  adapted  to  the 
driving  of  tricycles  by  Professors  Ayrton  and  Perry.  The 
motor  is  suspended  beneath  a  platform  under  the  seat, 
and  is  driven  by  several  cells  of  storage-battery,  which 
are  supported  on  a  second  and  lower  platform.  The 
machine  has  been  driven  at  a  speed  of  about  six  miles  per 
hour. 

Electric  launches  have  also  been  constructed.  One 
built  by  Messrs.  Yarrow  &  Co.,  in  1883,  measures  forty 
feet  in  length  by  six  feet  beam,  and  is  capable  of  carry- 
ing forty  passengers.  The  motor  is  a  Siemens  machine, 
driven  by  a  storage-battery ;  the  weight  of  motor  and  bat- 
teries being  about  two  and  a  quarter  tons.  The  speed  of 
the  boat  is  about  eight  miles  per  hour.  For  the  propul- 
sion of  ships'  boats,  electrical  motors  possess  marked 
advantages  over  steam-engines  ;  as  an  electric  launch  is 
much  more  easily  swung  from  a  ship's  davits  than  a  steam- 
launch,  it  has  no  fire  to  be  put  out  in  case  of  shipping 
seas,  and  the  machinery  will  work  under  water. 

The  application  of  an  electric  motor  to  the  guiding  of  a 
balloon  has  been  made  by  M.  Gaston  Tissandier,  with 
fairly  successful  results.  The  balloon  used  was  lenticular 
in  form.  The  motor  was  arranged  in  the  car,  and  caused 
to  rotate  a  large  propelling-fan.  The  current  was  obtained 
from  a  number  of  bichromate-of-potash  batteries.  The 
motor  was  so  arranged  that  its  speed  might  be  varied  from 
sixty  to  a  hundred  and  eighty  revolutions  per  minute. 
With  the  high  speed,  the  forward  motion  of  the  balloon 


ELECTRO-MOTORS.  177 

under  the  influence  of  its  propeller  was  plainly  observable, 
and  for  a  short  period  it  maintained  its  place  even  against 
a  moderate  breeze.  It  was  also  found  possible  to  swerve 
the  balloon  from  the  direction  of  the  wind. 

Telpherage  is  a  name  coined  by  the  late  Professor  Flee- 
ming  Jenkin,  to  designate  a  system  devised  by  him,  by 
which  the  transmission  of  vehicles  by  electricity  to  a  dis- 
tance is  effected  independently  of  any  control  exercised 
from  the  vehicle.  It  is  an  aerial  electrical  railway,  as  at 
present  projected,  in  which  the  track  is  either  a  single  or 
double  wire  rope  from  which  the  carriages  or  skips  are 
suspended.  The  line  is  divided  into  sections,  each  a  hun- 
dred and  twenty  feet  in  length ;  and  each  section  is  in- 
sulated from  its  neighbor.  A  train  is  made  up  of  a  loco- 
motive and  a  series  of  skips  held  at  uniform  intervals 
apart  by  wooden  poles  extending  from  skip  to  skip.  The 
skips  hang  below  the  line  from  V-wheels  supported  by 
arms  which  project  out  sideways  so  as  to  clear  the  sup- 
ports at  the  posts  :  the  motor  or  dynamo  on  the  locomo- 
tive is  also  below  the  line.  The  entire  train  is  a  hundred 
and  twenty  feet  in  length,  the  same  length  as  that  of  a 
section.  A  wire  connects  one  pole  of  the  motor  with  the 
leading- wheel  of  the  train,  and  a  second  wire  connects 
the  other  pole  with  the  trailing-wheel :  the  other  wheels 
are  insulated  from  each  other.  Thus  the  train,  wherever 
it  stands,  bridges  a  gap  separating  the  insulated  from  the 
uninsulated  section.  The  insulated  sections  are  supplied 
with  electricity  from  a  dynamo  driven  by  a  stationary 
engine  ;  and  the  current  passing  from  the  insulated  section 
to  the  uninsulated  section,  through  the  motor,  drives  the 
locomotive.  This  wilt  be  easily  understood  from  the  dia- 
gram Fig.  84.  Here  one  pole  of  the  dynamo  is  connected 
to  the  left-hand  extremity  of  the  conductor  represented  by 
the  continuous  line  ;  the  other  pole  being  connected  to  the 


178  THE  AGE  OF  ELECTRICITY. 

uninsulated  line  shown  dotted.  M  and  ^/"represent  two 
trains.  When  these  are  in  the  position  shown,  it  will  be 
evident  that  a  portion  of  the  dynamo  current  will  go 
through  each  train  as  indicated  by  the  arrows ;  and  this 
current  passing  through  the  motor  in  the  locomotive  sets 
it  in  motion,  and  so  propels  the  train. 


Vhinmtdfad 


Fig.  84. 

Another  arrangement,  called  the  series  system,  is  illus- 
trated in  the  diagram  Fig.  85.  Here  there  is  but  a  single 
wire,  on  which  the  trains  are  supported  ;  this  consisting  of 
a  series  of  spans.  The  breaks  between  these  spans  are 
normally  kept  closed  by  means  of  switches.  Each  switch 
is  opened  automatically  as  soon  as  a  train  bridges  it,  so 


Fig.  85. 

that  the  current  is  thus  caused  to  pass  through  the  train, 
and  so  keep  it  in  motion.  When  a  train  has  passed  over 
a  break,  the  switch  is  automatically  closed,  so  that  the 
continuity  of  the  circuit  through  the  wire  is  preserved. 

Telpherage  is  as  yet  in  its  infancy,  and,  in  fact,  has  not 
been  tried  on  a  sufficiently  extensive  scale  to  determine 


ELECTRO-MO  TOES. 


179 


even  the  most  salient  questions  bearing  upon  its  econom- 
ical efficiency.     So  far  as  can  be  foreseen,  the  invention 


bids  fair  to  be  of  great  practical  value.  Professor  Jenkin 
has  pointed  out  that  "  wherever  railways  and  canals  do 
not  exist,  telpher  lines  will  provide  the  cheapest  mode  of 


180  THE  AGE  OF  ELECTRICITY. 

inland  conveyance  for  all  goods  such  as  corn,  coal,  root- 
crops,  herrings,  hides,  etc.,  which  can  be  conveniently  sub- 
divided into  parcels  of  one,  two,  or  three  hundred  weight. 
In  new  colonies,  the  lines  will  often  be  cheaper  to  make 
than  roads,  and  will  convey  goods  far  more  cheaply.  In 
war  they  will  give  a  ready  means  of  sending  supplies 
to  the  front.  Moreover,  wherever  a  telpher  line  exists, 
power  is  thereby  laid  on  ;  and  this  power  may  be  used  for 
other  purposes  than  locomotion.  A  flexible  wire  attached 
to  the  line  will  serve  to  drive  a  one,  two,  or  three  horse 
engine,  which  may  be  used  for  any  imaginable  purpose, 
such  as  digging,  mowing,  threshing,  or  sawing."  Tel- 
pher lines  will  also  act  as  "  feeders  of  great  value  to  the 
railways,  extending  into  districts  which  could  not  support 
the  cost  even  of  the  lightest  railway."  Fig.  86,  from  a 
photograph,  represents  Professor  Jenkin's  first  line.  The 
buckets,  or  skips,  weighed  about  three  hundred  pounds 
each,  the  locomotive  the  same.  Each  skip  carried  as  a 
useful  load  about  two  hundred  and  fifty  pounds.  The 
projected  speed  was  five  miles  per  hour,  at  which  it  was 
estimated  about  ninety-two  and  a  half  tons  hourly  of 
freight  could  be  conveyed. 

General  Thayer,  U.S.A.,  has  devised  a  remarkable  sys- 
tem of  war  balloons,  which  are  designed  to  travel  upon 
wires  or  light  cables  stretched  across  the  country  on  ordi- 
nary poles.  The  balloon  itself  is  in  the  shape  of  a  cir- 
cular spindle,  and  supports  a  deck  for  the  transport  of 
troops,  cannon,  etc.  The  electricity  is  generated  at  the 
end  of  the  line,  and  is  conveyed  along  the  wires  to  a  motor 
on  the  deck  of  the  balloon.  The  motor  drives  the  wheels 
which  impel  the  balloon  along  the  cable.  General  Thayer 
states  that  such  a  road  could  be  built  at  the  rate  of  from 
three  to  four  miles  a  day,  at  a  cost  of  fifteen  hundred  dol- 
lars per  mile,  and  the  speed  attained  might  be  from  sixty 


ELECTRO-MOTORS.  181 

to  seventy  miles  per  hour.  The  wire  could  be  run  across 
country  in  a  direct  line,  where  it  would  be  impossible  to 
build  a  railway.  Men  and  ammunition  could  thus  be 
rapidly  transported ;  and,  as  an  army  advances  into  an 
enemy's  country,  the  balloon-way  could  be  put  up  in  its 
rear,  and  thus  establish  a  line  of  communication  with  its 
base  of  supplies. 


182  THE  AGE  OF  ELECTRICITY. 


CHAPTER   X. 

ELECTROLYSIS.  ELECTRO-METALLURGY    AND    THE    STORAGE- 
BATTERY. 

IN  the  galvanic  battery  a  chemical  re-action  takes  place, 
and  the  result  is  the  production  of  an  electric  current.  If, 
conversely,  we  place  in  a  decomposable  liquid  two  con- 
ducting bodies,  and  thus  enable  a  current  of  electricity  to 
pass  through  the  liquid,  we  shall  find  that  the  result  is  a 
chemical  decomposition.  This  decomposition  by  means 
of  the  electric  current  is  called  electrolysis  ;  the  liquid 
decomposed  is  known  as  an  electrolyte,  and  the  two  con- 
ducting bodies  are  termed  electrodes.  In  a  galvanic  cell, 
a  definite  amount  of  chemical  action  evolves  a  current, 
and  transfers  a  certain  quantity  of  electricity  through  the 
circuit :  so,  conversely,  a  definite  quantity  of  electricity, 
in  passing  through  an  electrolytic  cell,  will  perform  a 
definite  amount  of  chemical  work.  An  electrolytic  cell 
is,  therefore,  the  converse  of  a  voltaic  cell. 

The  discovery  of  the  decomposing  effects  of  the  electric 
current  was  made  by  accident,  and  followed  almost  im- 
mediately after  the  invention  of  Volta's  pile.  Volta 
addressed  a  letter  to  Sir  Joseph  Banks,  then  President 
of  the  Royal  Society,  on  March  20,  1800,  wherein  he  an- 
nounced the  discovery  of  his  pile.  The  first  portion  only 
of  this  letter,  which  described  the  construction  of  the  ap- 
paratus, was  sent  on  the  above  date ;  and  the  remainder 


ELECTROLYSIS.  183 

followed  during  the  succeeding  month  of  June.  Until  the 
latter  date,  the  whole  missive  was  not  published ;  but  in 
the  meanwhile  Sir  Joseph  Banks  showed  such  parts  as  he 
had  received,  to  Mr.  W.  Nicholson  and  Mr.  (afterwards 
Sir)  Anthony  Carlisle.  These  two  gentlemen  at  once  con- 
structed a  pile  composed  of  silver  half-crown  pieces,  alter- 
nated with  equal  disks  of  copper,  and  cloth  soaked  in 
a  weak  solution  of  common  salt.  It  so  happened,  that  a 
drop  of  water  was  used  to  make  good  the  contact  of  the 
conducting  wire  with  a  plate  to  which  the  electricity  was 
to  be  transmitted.  In  noticing  this,  Carlisle  observed  a 
disengagement  of  gas  from  the  water  ;  and  Nicholson  rec- 
ognized the  "odor  of  hydrogen  "  coming  from  it.  They  at 
once  took  measures  to  determine  the  cause  of  this  singular 


Pile 


Fig.  87. 


effect ;  and,  using  the  first  materials  at  hand,  filled  a  piece 
of  glass  tube  with  water,  plugging  both  ends  with  cork, 
and  inserting  through  each  cork  a  piece  of  brass  wire,  as 
shown  in  Fig.  87.  When  the  wires  P  and  N  were  put  in 
communication  with  opposite  ends  of  the  pile,  bubbles  of 
gas  were  evolved  from  the  point  of  the  wire  by  which  the 
current  left  the  tube,  and  the  end  of  the  wire  by  which 
the  current  entered  became  tarnished.  The  gas  evolved 
appeared  on  examination  to  be  hydrogen  ;  and  the  tarnish 
was  found  to  proceed  from  the  oxidation  of  the  entrance, 
or  positive,  wire.  In  order  to  prevent  this  oxidation  of 
the  material  of  the  wire  itself,  another  apparatus  was 
made,  in  which  platinum  wires  were  used.  Then  gas  was 
evolved  from  both  wires  ;  and  this,  ascending  through  the 


184  THE  AGE   OF  ELECTRICITY. 

water,  was  collected  separately  in  two  tubes.  The  con- 
tents of  the  tubes  being  examined,  hydrogen  was  found 
in  one,  and  oxygen  in  the  other ;  the  two  gases  being 
almost  exactly  in  the  proportions  known  to  constitute 
water. 

In  this  way  the  decomposing  power  of  the  electric  cur- 
rent was  established  very  shortly  after  the  first  knowledge 
of  Volta's  invention  had  reached  England.  Of  course, 
experiments  so  remarkable  attracted  the  attention  of  other 
investigators.  Cruickshank  decomposed  a  variety  of  com- 
pound substances,  and  found,  that,  as  a  consequence  of 
decomposition,  the  acids  and  oxygen  always  collected 
around  the  positive  wire,  by  which  the  current  came  in  ; 
and  hydrogen,  metals,  and  the  alkalies,  around  the  nega- 
tive wire,  by  which  the  current  went  out.  The  pile  as 
Volta  had  made  it  became  manifestly  inadequate  to  the 
production  of  the  strong  and  uniform  currents  that  were 
needed  ;  and  to  meet  this  want  Cruickshank  devised  his 
well-known  trough  battery,  in  which  zinc  and  copper 
plates  were  fixed  in  vertical  grooves,  the  liquid  being  in- 
terposed between  the  successive  pairs  of  plates.  Cruick- 
shank's  battery,  or  modifications  of  it,  are  still  in  common 
use. 

Meanwhile,  a  young  German  chemist,  Ritter  of  Jena, 
had  also  independently  discovered  the  electro-decomposi- 
tion of  water  and  saline  compounds  ;  and,  more  than  this, 
he  had  found  out  that  this  singular  decomposing  power 
could  be  transmitted  through  sulphuric  acid,  so  that,  if  on 
both  sides  of  the  acid  there  were  water,  oxygen  and  hydro- 
gen would  still  be  evolved  from  the  wires  clipping  in  the 
water.  It  seemed,  therefore,  that  one  or  the  other  of  the 
elements  of  water  must  have  passed  through  the  sulphuric 
acid :  for,  clearly,  if  the  water  was  decomposed  at  the 
positive  wire,  where  only  oxygen  appeared,  the  hydrogen 


ELECTROLYSIS.  185 

must  somehow  get  across  to  the  negative  wire  ;  while,  if 
the  decomposition  occurred  at  the  negative  wire,  then 
oxygen  must  also  in  some  unexplained  way  cross  over  to 
the  positive  wire. 

This  was  the  singular  phenomenon  which  attracted  the 
notice  of  a  scientific  student  who  was  then  just  com- 
mencing the  labors  which  earned  for  him  an  imperish- 
able name.  Humphry  Davy  wondered  whether,  if  the 
two  wires  were  immersed  each  in  a  glass  of  pure  water, 
the  gases  would  be  produced.  He  tried  it :  nothing 
happened.  Then  he  put  a  finger  of  his  right  hand  in 
one  glass,  and  a  finger  of  his  left  hand  in  the  other. 
It  was  very  extraordinary :  then  the  gases  appeared. 
Next  he  got  three  people  to  stand  in  a  row,  hand  in 
hand,  forming  a  chain  between  the  glasses :  still  the 
gases  appeared.  It  was  a  simple  experiment,  —  the  ex- 
periments of  most  great  thinkers  are  simple, — but  it 
demonstrated  conclusively,  that,  if  any  material  princi- 
ple passed  between  the  wires,  it  must  have  been  trans- 
mitted through  his  body,  or  the  bodies  of  all  three 
people  who  formed  the  line  of  communication  between 
the  gases. 

Then  in  October,  1800,  began  Davy's  famous  experi- 
ments which  stand  and  will  stand  forever  as  the  founda- 
tions of  a  great  branch  of  electrical  science.  Beginning 
upon  the  voltaic  pile  itself,  he  found  that  the  chemical 
changes  in  it  were  the  cause  of  its  electrical  effects,  and 
that  the  action  in  a  cell  is  similar  to  the  decomposition  of 
water  at  the  extreme  wires  of  the  pile  ;  that  a  battery 
could  be  made  of  liquid  elements  with  conducting-plates 
of  identical  material  placed  in  them.  And  then,  branching 
from  the  chemical  to  the  calorific  properties  of  the  battery, 
he  constructed  a  huge  apparatus  whereby  he  fused  wire, 
and  for  the  first  time  produced  the  electric  arc  between 


186  THE  AGE  OF  ELECTRICITY. 

carbon  points.  Brilliant  as  Davy's  discoveries  then  were, 
they  were  merely  the  prelude  of  others  which  startled  the 
world. 

When  water  was  first  decomposed,  it  was  noted  that  at 
the  positive  electrode  there  were  always  present  indica- 
tions of  an  acid,  while  at  the  negative  electrode  an  alkali 
appeared.  There  were  not  wanting  philosophers  who 
jumped  to  the  conclusion  that  here  were  new  things  in 
water,  not  known  in  anybody's  philosophy.  One  wanted 
to  suppose  an  "electric  acid," — a  neat  example  of  the 
art  of  explaining  something  which  is  not  understood,  by 
giving  a  name  to  it.  Another  insisted  that  the  acid  and 
alkali  were  ' '  generated  ' '  out  of  the  elements  of  the  water 
by  voltaic  action  ;  thus  anticipating  the  later  claims  to 
other  singular  things  ' '  generated ' '  from  water  by  the 
inventor  of  the  so-called  Keely  motor.  One  peculiarly 
conscienceless  individual  announced  that  the  most  care- 
fully distilled  water  nevertheless  yielded  "muriate  of 
soda."  Why  "muriate  of  soda,"  he  failed  to  explain; 
and  some  people,  anxious  to  know  about  this,  who  called 
at  the  address  appended  to  his  memoir,  came  back, 
and  said  that  nobody  of  the  author's  name  lived  there. 
Altogether,  although  the  fact  of  electro-decomposition 
had  been  established,  the  subject  as  a  wrhole  was  in  a 
state  of  confusion  ;  and  it  was  to  bring  order  but  of 
this  chaos,  that  Davy  resumed  his  investigations  into 
electro-chemistry. 

The  first  thing  he  did  was  to  explode  thoroughly  and  elabo- 
rately the  notion  that  any  thing  but  hydrogen  and  oxygen 
could  be  got  out  of  water  ;  provided  the  water  was  pure,  and 
such  disturbing  causes  as  acids  and  alkalies  in  the  vessels 
used  were  eliminated,  —  not  in  the  vessels  in  the  sense  of 
contained  in  them,  but  in  their  substance,  be  it  noted. 
And  from  this  singular  circumstance,  that  the  current 


ELECTROLYSIS. 


187 


was  powerful  enough  to  drag  acids  and  alkalies  out  of 
the  very  material  of  cups  of  agate  and  glass,  grew  the 
idea  that  the  same  power  might  be  brought  to  bear  on 
other  bodies,  and  thus  force  from  substances  hitherto 
considered  simple  and  elementary,  the  secrets  of  their 
complex  composition. 

Davy's  first  efforts  were  directed  to  potash.  The  alkali 
liquefied  by  heat  was  placed  on  a  platinum  disk,  which 
was  connected  with  the  negative  pole  of  a  battery,  while 
a  wire  connected  with  the  positive  pole  was  applied  to  its 
upper  surface.  At  the  upper  surface  there  was  a  dis- 
engagement of  gas  ;  at  the  lower  surface,  small  metallic 
globules  appeared,  like  mercury  in  appearance.  Some  of 
these  burned  by  contact 
with  air.  The  gas  dis- 
engaged at  the  positive 
wire  was  oxygen  ;  and 
the  metal  deposited  was 
the  base  of  the  alkali 
afterwards  called  po- 
tassium, thus  for  the 

first  time  revealed.  In  like  manner,  from  soda  Davy  pro- 
duced the  metal  sodium ;  and  then  from  baryta,  strontia, 
lime,  and  magnesium,  came  barium,  strontium,  calcium, 
and  magnesium.  Still  more  refractory  materials  were  then 
attacked ;  and  alumina,  silica,  zirconia,  and  glucinia 
yielded  silicium,  aluminum,  glucinium,  and  zirconium. 

Davy  not  only  found  that  the  electric  current  was  capa- 
ble of  decomposing  compound  bodies,  but  also  of  trans- 
ferring—  or,  if  the  term  maybe  permitted,  of  decanting 
—  their  constituents  from  one  vessel  to  another.  Some 
of  the  results  of  his  experiments  were  most  singular. 
Three  cups  were  arranged  as  shown  in  Fig.  88  ;  the  posi- 
tive wire  entering  the  cup  P,  and  the  negative  wire  enter- 


Fig.  88. 


188  THE  AGE  OF  ELECTRICITY. 

ing  the  cup  N.  I  is  an  intermediate  cup,  between  which 
and  the  cups  P  and  ^V  extend  strips  of  asbestos,  A,  which 
act  as  siphons.  The  current  then  passed  from  the  positive 
wire  through  the  liquid  in  cup  P,  thence  by  the  asbestos 
through  the  liquid  in  cup  /,  by  the  asbestos  again  to  the 
liquid  in  cup  JV,  and  so  out  to  the  negative  wire.  The 
negative  cup  jVwas  filled  with  a  solution  of  sulphate  of 
potash ;  the  centre  cup,  with  water  in  which  litmus  had 
been  infused ;  and  the  positive  cup  P  contained  simply 
distilled  water.  When  the  current  passed,  the  acid  con- 
stituent of  the  sulphate  of  potash  should  appear  at  the 
positive  pole  P ;  but,  to  get  there,  it  obviously  would 
have  to  traverse  the  litmus  solution  in  the  middle  cup  /. 
Now,  litmus  is  a  very  delicate  test  for  the  presence  of  an 
acid,  inasmuch  as,  normally  dark  blue,  it  at  once  reddens 
when  acid  is  added  to  it ;  and  hence  the  passage  of  the 
acid  should  thus  be  at  once  revealed.  But,  strange  to  say, 
although  the  acid  of  the  sulphate  went  over  to  the  positive 
pole,  and  actually  through  the  litmus  solution,  no  redden- 
ing of  the  latter  followed.  If  the  acid  thus  seemingly 
lost  its  power,  in  transit,  to  affect  vegetable  solutions, 
what  would  happen  if  a  strong  alkali  were  put  in  the 
middle  cup?  Would  the  acid  and  alkali  instantly  rush 
together  by  reason  of  their  affinity,  as  they  had  done  since 
the  beginning  of  the  world  ?  No :  sulphuric  acid  went 
directly  through  a  solution  of  ammonia,  without  produ- 
cing chemical  change.  Hydrochloric  and  nitric,  strongest 
of  the  acids,  were  driven  through  concentrated  alkalies  : 
conversely,  strong  alkalies  were  passed  through  strong 
acids.  It  seemed  as  if  either  alkali  or  acid,  when  in  the 
control  of  the  current,  was  powerless  until  the  current 
had  forced  it  to  its  destination.  One  exception  appeared 
to  this  rule :  sulphuric  acid  could  not  be  driven  through 
stroutia  or  baryta,  nor  the  latter  through  sulphuric  acid ; 


ELECTROLYSIS.  189 

precipitation  occurred  in  the  middle  cup.  The  result  of 
the  affinity  was,  however,  an  insoluble  substance  ;  and  so 
it  was  determined,  that,  wherever  the  element  transmitted 
forms,  with  the  medium  through  which  it  passes,  an 
insoluble  compound,  the  passage  is  stopped.  But  that  in 
other  cases  the  transmission  did  go  on,  and  the  affinities 
of  the  substances  were  suspended,  was  evident  from  the 
fact,  that,  when  the  current  was  broken  for  a  moment, 
combination  of  acid  molecules  with  the  alkali  through 
which  they  were  travelling  instantly  occurred. 

In  1826  Nobili  discovered,  that  when  a  current  of  elec- 
tricity is  passed  into  a  solution  of  acetate  of  lead  by 
means  of  a  plate  of  platinum,  and  out  of  it  by  means  of  a 
platinum  wire,  rings  of  beautiful  colors,  caused  by  the  for- 
mation of  thin  films  of  peroxide  of  lead,  appeared  on  the 
platinum  plate.  These  colors  are  very  like  those  produced 
on  steel  in  tempering,  and  on  the  surface  of  molten  lead, 
which  are  due  to  a  film  of  oxide  overspreading  the  metal. 

In  another  chapter  we  have  alluded  to  the  splendid 
discoveries  in  magneto-electricity,  made  by  Faraday  in 
1831.  Three  years  later  he  supplemented  these  with 
the  investigations  which  established  the  laws  of  electro- 
chemistry. He  found  that  the  amount  of  chemical  action 
in  the  cell  is  always  proportional  to  the  quantity  of  elec- 
tricity passing  through  it ;  and  that  the  quantities  of  sub- 
stances dissolved  and  set  free  by  electrolysis  are  in  definite 
proportions  by  weight,  and  these  proportions  are  identical 
with  the  ordinary  chemical  equivalents  of  the  substances. 
From  the  first  law  we  know  that  a  current  of  a  certain 
strength  will  always  liberate  just  so  much  hydrogen,  for 
example,  from  water,  and  will  cause  the  solution  of  just 
so  much  zinc  in  the  cell  whence  the  current  is  derived. 
To  illustrate  the  second  law:  nine  grains  of  water,  for 
example,  contain  eight  grains  of  oxygen  and  one  grain 


190 


THE  AGE  OF  ELECTRICITY. 


of  hydrogen  ;  and  hydrogen  and  oxygen  always  combine 
in  these  proportions  to  form  water.  Now,  if  we  tear 
apart,  so  to  speak,  the  constituents  of  water,  we  shall 
always  find  eight  grains  of  oxygen  at  the  positive  elec- 
trode, and  one  grain  of  hydrogen  at  the  negative  electrode. 
Why  this  happens,  is  not  definitely  proved  ;  but  the  gen- 
erally accepted  theory,  that  of  Grothuss,  is  neatly  illus- 
trated in  the  accompanying  engraving,  Fig.  89,  which 
represents  the  case  of  hydrochloric  acid,  each  molecule 
of  which  is  composed  of  one  atom  of  hydrogen  and  one 
atom  of  chlorine.  The  plate  A  is  the  positive  electrode, 

and  the  plate  B  the  neg- 

f-l  \\        ative    electrode.      The 

oval  objects  are  sup- 
posed to  represent  the 
molecules ;  the  white 
half  of  each  represent- 
ing chlorine,  and  the 
dark  half  hydrogen. 
The  row  marked  1 
shows  the  molecules 
distributed  at  random,  as  before  the  current  passes.  When 
the  current  is  established,  the  molecules  arrange  them- 
selves in  innumerable  chains  in  which  every  molecule  has 
its  constituent  atoms  pointing  in  a  certain  direction ;  for, 
as  we  see,  all  the  chlorine  atoms  point  to  the  positive  plate 
A,  and  all  the  hydrogen  atoms  to  the  negative  plate  B. 
Now,  if  the  current  is  strong  enough,  the  chlorine  half  of 
the  molecule  next  the  positive  plate  is  divorced  from  its 
wedlock  with  the  hydrogen  half.  Atoms  abhor  celibacy. 
They  are  polygamous  or  polyandrous  to  the  last  degree ; 
but  single-blessedness  they  will  have  none  of  if  they  can 
help  it.  So,  no  sooner  is  the  hydrogen  atom  off  with  the 
old  love,  before  it  is  immediately  on  with  the  new  ;  because 


Fig.  89. 


ELECTROLYSIS.  191 

it  promptly  appropriates  the  chlorine  partner  of  its  next 
neighbor.  The  thus  deserted  hydrogen  atom  helps  him- 
self to  his  neighbor's  consort  in  like  manner ;  and  so  on 
through  this  singular  chain,  until  at  last  there  is  a  hydrogen 
atom  left  solitary  and  alone  at  the  negative  plate,  matching 
the  solitary  chlorine  atom  at  the  positive  plate,  as  in  row 
3.  And  so  it  looks  as  if  all  the  chlorine  atoms  had  some- 
how made  their  way  to  one  plate,  and  all  the  hydrogen 
atoms  to  the  other.  Faraday  called  these  apparently 
migrating  atoms  ions  ;  and  gave  the  name  anode  to  the 
positive  plate,  and  cathode  to  the  negative  plate.  Then 
the  ions  which  went  to  the  anode  were  termed  anions  ; 
and  those  which  appeared  at  the  cathode,  cathions. 

There  was  a  grave  and  dignified  professor  once,  who  by 
dint  of  much  persuasion  was  induced  to  attend  a  dancing- 
party.     Among  the  complicated  figures  of   the  German, 
there  was  one  in  which  the  several  couples  interchanged 
partners  until  a  single  couple  were  left  unmated.     The 
professor,    who    had   regarded   the   proceedings    hitherto 
rather  stoically,  and  with  a  somewhat  bored  expression, 
suddenly    brightened,    and    emitted    a    peculiar    pleased 
chuckle  which  the  writer  well  knew  from  past  experience 
was  of  the  same  character  as  that  which  always  followed 
a  neat  bit  of  scientific  demonstration,  accompanied  by  a 
muttered  "  Beautiful,  ah,  beautiful !  " 
u  Who,  professor?"  was  asked. 
"Who?     Nobody.     It's  what  they're  doing." 
"  Oh,  — the  German  figure.     Yes,  it  is  rather  "  — 
"German  figure?     Oh,  you  mean  Grothuss,  of  course. 
But  now,  doesn't  that  —  doesn't  this  interchange  of  the 
women  beautifully  —  beautifully  illustrate  his  idea  of  the 
migration  of  the  ions?     Eh?  " 

Two  years  after  Faraday  had  made  his  discoveries,  De 
la  Rue  observed  the  singular  fact,  that  in  a  peculiar  form  of 


192  THE  AGE  OF  ELECTRICITY. 

Daniell's  battery  the  copper  plate  became  covered  with  a  coat- 
ing of  metallic  copper,  which  took  the  exact  impress  of  the 
plate,  even  to  the  fine  scratches  upon  it.  In  1837  Dr.  Gold- 
ing  Bird  decomposed  the  chlorides  of  sodium,  potassium, 
and  ammonium,  and  deposited  their  respective  metals  on  a 
negative  pole  of  mercury,  thus  obtaining  their  amalgams. 

It  would  have  been  almost  a  phenomenal  occurrence  if 
the  discovery  soon  to  be  made,  and  which  ultimately  be- 
came of  such  great  industrial  importance,  should  have 
failed  to  have  more  than  a  single  claimant ;  but  the  pro- 
cess of  electrotypiug  differs  from  most  other  electrical 
discoveries  in  that  all  the  claimants  appeared  at  once,  and 
did  not  come  stringing  along  after  the  manner  of  their 
kind,  for  years  after  some  one,  bolder  than  the  others,  had 
announced  his  success.  In  1839  Jacobi  in  St.  Petersburg, 
Spencer  in  Liverpool,  and  Jordan  in  London,  described 
independently  a  method  of  converting  any  line,  however 
fine,  engraved  on  copper,  into  a  relief,  by  galvanic  pro- 
cess, —  by  depositing  copper  upon  the  engraved  object. 
Jacobi  published  his  description  in  a  newspaper ;  Jor- 
dan wrote  a  letter  to  the  editor  of  "The  Mechanics' 
Magazine;"  and  Spencer,  last  of  all,  read  a  paper  on 
the  subject  before  the  Liverpool  Polytechnic  Society,  — 
all  in  the  same  year.  Their  respective  adherents  argued 
about  their  respective  priority  of  invention,  quite  steadily 
in  the  public  prints,  for  the  next  three  years,  and  inter- 
mittently contradicted  one  another  for  some  time  after- 
wards. Spencer  wrote  the  best  account  of  what  he  had 
done,  —  despite  the  fact  that  his  opponents  sneered  at  him 
for  being  only  a  carver  and  gilder,  and  not  a  professor, 
which  to  their  minds  logically  disproved,  of  course,  his 
pretensions,  —  and  the  general  public  somehow  understood 
what  he  wrote  about ;  for,  as  a  recent  writer  remarks, 
u  thousands  of  persons,  of  all  classes  of  society,  at  once 


ELECTROLYSIS.  193 

became  fascinated  by  the  new  art.*'  At  about  this  time 
the  Elkingtons  of  London  began  coating  military  and  other 
metal  ornaments  with  gold  and  silver,  simply  by  immersing 
them  in  solutions  of  those  metals.  In  1840  John  Wright, 
a  surgeon  of  Birmingham,  came  to  them  with  the  news 
that  he  had  succeeded  in  obtaining  electrically  a  thick, 
firm,  and  white  deposit  of  silver,  upon  articles  treated  in 
a  liquid  made  by  dissolving  the  cyanide  of  this  metal  in 
an  alkaline  cyanide.  The  Elkingtons  saw  the  value  of 
his  discovery,  and  did  what  would  have  been  impossible 
in  this  country, — embodied  Wright's  idea  in  their  patent; 
not  for  the  purpose  of  depriving  Wright  of  his  reward, 
but  in  order  to  perfect  and  complete  the  description  of  a 
process  which  proved  to  be  the  basis  of  all  successful 
electroplating  of  gold  and  silver.  Wright,  in  fact,  profited 
well,  for  he  was  paid  a  royalty  of  one  shilling  an  ounce 
for  every  ounce  of  silver  deposited  ;  and  a  handsome 
annuity  was  settled  on  his  widow  after  his  death. 

The  history  of  electro-chemistry  from  this  point  is  that 
of  technical  details,  out  of  place  here  ;  so  that  we  pass  at 
once  to  practical  applications,  and  these  are  fourfold : 
first,  electrotyping,  or  the  copying  of  types,  casts,  or  other 
objects,  by  deposits  of  metal ;  second,  electroplating,  or 
the  covering  or  plating  of  objects  of  baser  metal,  with  a 
thin  film  of  another  metal,  usually  gold  or  silver ;  third, 
the  reduction  of  metals  from  solutions  of  their  ores ;  and, 
fourth,  the  secondary  or  storage  battery. 

Electrotyping  finds  its  widest  utilization  in  the  repro- 
duction of  engravings  and  pages  set  in  type.  A  mould 
of  the  object,  made  in  wax,  lightly  covered  with  plumbago 
so  that  a  conducting  surface  may  be  present,  is  placed  in 
a  bath  of  saturated  solution  of  sulphate  of  copper,  and 
attached  to  the  cathode,  or  pole  at  which  the  current  leaves 
the  bath.  A  plate  of  copper  is  attached  to  the  anode,  or 


194  THE  AGE   OF  ELECTRICITY. 

wire  at  which  the  current  enters.  This  plate  is  decom- 
posed at  the  same  rate  as  the  copper  is  deposited  from  the 
solution,  on  the  plumbago-covered  surface  of  the  mould ; 
and  in  this  way  the  strength  of  the  solution  is  kept  uni- 
form. The  copper,  as  it  is  deposited,  covers  every  por- 
tion of  the  surface  with  a  bright  layer,  usually  starting 
from  the  suspending  wire  and  extending  itself  gradually 
over  the  entire  area.  Generally  the  electrotyping  opera- 
tion takes  about  twenty-four  hours  ;  but  for  newspaper 
work  this  time  is  necessarily  much  shortened.  It  is  not 
uncommon  for  pages  of  illustrated  papers,  especially  if 
containing  important  engravings  of  recent  events,  to  be 
electrotyped  in  eight,  six,  and  even  four  hours. 

When  a  good  adherent  film  of  copper  has  been  depos- 
ited over  the  surface,  the  mould  is  removed.  The  wax 
is  melted  to  liberate  the  electrotype,  which  is  then  backed 
with  an  alloy  of  lead,  antimony,  and  tin.  The  plate  thus 
produced  is  an  absolutely  exact  reproduction  of  the  origi- 
nal types  or  relief  engraving  from  which  the  wax  mould 
was  made.  It  only  remains  to  mount  the  plate  upon  a 
block  of  wood,  type  high,  when  it  is  ready  to  take  its 
place  in  the  form  which  is  placed  in  the  printing-press. 
Usually  the  woodcuts  and  types  are  set  up  and  arranged  in 
page  form,  and  then  the  whole  page  is  electrotyped.  The 
pages  before  the  reader  have  been  thus  prepared.  When 
an  electrotype  is  to  be  submitted  to  hard  usage,  — as  when 
a  great  many  impressions  are  to  be  taken  from  it,  —  it  is 
sometimes  coated  with  a  pellicle  of  electrically  deposited 
iron.  Messrs.  Christofle  &  Co.  of  Paris  have  recently 
made  very  beautiful  electrotypes  by  the  direct  deposition  of 
nickel  in  the  mould,  strengthened  by  a  copper  backing. 

The  electrotyping  process  has  been  used  on  a  large 
scale  for  the  reproduction  of  statues  of  even  colossal  di- 
mensions. In  such  cases,  instead  of  making  moulds  the 


ELECTROLYSIS.  195 

plaster-of -Paris  figure  itself  is  sacrificed.  The  mode  of 
operation  is  interesting. 

After  the  figure  is  well  saturated  in  linseed  oil,  it  is 
covered  with  a  film  of  black-lead,  and  then  placed  in 
a  large  cistern  of  sulphate-of-copper  solution,  which  is 
allowed  to  precipitate  its  copper  on  the  object  until  a  coat- 
ing is  formed  of  about  one-sixteenth  of  an  inch  in  thick- 
ness. The  object  is  then  lifted  from  the  bath,  the  copper 
envelope  cut  through  at  suitable  places,  the  plaster  figure 
broken  away  with  great  care,  and  the  whole  of  it  extracted. 
The  outer  surfaces  of  the  copper  forms  (with  wires 
attached)  are  now  thoroughly  varnished  all  over,  to  pre- 
vent any  deposit  being  formed  thereon  ;  the  forms  exposed 
to  sulphuretted  hydrogen,  to  prevent  adhesion  of  the  depos- 
it ;  and  the  parts  are  immersed  in  the  depositing- vat  again, 
which  is  filled  with  copper  solution.  A  dissolving  plate  of 
pure  electrotype  copper  is  suspended  within  each  portion, 
and  a  deposit  of  copper  thus  formed  all  over  its  interior, 
until  a  considerable  thickness,  varying  from  one-eighth  to 
one- third  of  an  inch,  is  deposited,  which  requires  a  period 
of  three  or  four  weeks.  Each  piece  is  now  removed  from 
the  liquid,  washed,  and  the  outer  shell  torn  off ;  when  all 
the  parts  of  the  figure  remain  nearly  complete,  and  ready 
for  fixing  together.  Some  of  the  objects  made  by  this 
process,  by  the  Messrs.  Elkington,  are  colossal.  The 
statue  of  the  Earl  of  Eglinton  is  thirteen  and  a  half  feet 
high,  and  weighs  two  tons  ;  and  the  vat  in  which  it  was 
formed  is  capable  of  holding  6,680  gallons  of  liquid. 
The  Messrs.  Christofle  made  a  statue  twenty-nine  feet  six 
inches  high,  and  weighing  about  five  and  a  half  tons. 
About  ten  weeks  were  required  to  deposit  the  metal. 

Electroplating  is  now  practised  with  a  great  variety  of 
metals.  The  ordinary  arrangement  of  a  silver-plating 
bath,  to  which  a  battery-cell  supplies  current,  is  represented 


196  THE  AGE  OF  ELECTEICITY. 

in  Fig.  90.  Of  late  years,  the  nickel-plating  of  all  sorts 
of  metal  articles,  from  the  parts  of  steam-engines  down 
to  surgical  instruments,  has  become  a  very  important 
branch  of  the  industry,  replacing  to  a  great  extent  gold 
and  silver  plating.  Nickel-plated  articles  take  a  fine  pol- 
ish, do  not  tarnish,  and  their  coating  is  hard  and  lasting. 
The  solutions  commonly  used  for  nickel-plating  were  in- 
vented by  Mr.  Isaac  Adams,  and  patented  in  this  coun- 
try in  1869.  They  may  be  the  double  chloride  of  nickel 
and  ammonium,  or  the  double  sulphate  of  nickel  and 


Fig.  90. 

ammonium  ;  the  bath  being  neutral,  that  is,  neither  acid 
nor  alkaline,  upon  which  fact  the  success  of  the  Adams 
process  greatly  depends.  The  cheapness  of  nickel,  and 
the  rapidity  with  which  it  is  deposited,  — from  fifteen  min- 
utes to  an  hour,  when  the  dynamo  is  used  to  supply  cur- 
rent, being  sufficient  time, — have  resulted  in  nickel-plating 
becoming  an  eveiy-day  process  in  many  engineering  work- 
shops. 

It  can  hardly  be  said,  however,  that  nickel-plating  is 
anywhere  carried  on  on  the  gigantic  scale  in  which  silver- 
plating  is  practised,  especially  in  Europe.  The  house  of 


ELECTROLYSIS.  197 

Cbristofle  &  Co.  in  Paris  annually  deposits  more  than  thir- 
teen thousand  pounds  of  silver,  and  since  its  establishment 
in  1842  has  used  not  less  than  a  hundred  and  eighty-five 
tons  of  that  metal. 

Gold  is  usually  deposited  from  the  double  cyanide  of 
gold,  and  potassium.  The  metal  is  sometimes  deposited 
in  solid  form  upon  moulds  for  the  production  of  articles 
of  jewellery  having  very  complex  or  under-cut  ornaments 
upon  them.  By  the  use  of  certain  solutions,  the  gold- 
plating  can  be  beautifully  colored  ;  and  in  this  way  the 
red  gold,  orange  gold,  etc.,  of  fashionable  jewellery,  are 
produced.  In  gilding  base  metals,  a  film  of  copper  or 
brass  is  generally  first  produced  upon  them.  The  insides 
of  vessels  are  gilded  by  filling  the  vessel  with  the  gold 
solution,  suspending  a  gold  anode  in  the  liquid,  and  pass- 
ing the  current.  Many  very  beautiful  objects  of  art  are 
made  by  incasing  in  gold,  silver,  and  copper,  for  exam- 
ple, ferns,  foliage,  flowers,  insects,  and  lizards.  So  also 
anatomical  specimens,  such  as  brains,  have  been  thus 
treated  ;  the  electro-deposit  preserving  every  minute  wrin- 
kle and  fissure.  An  even  more  grim  application  has  re- 
cently been  proposed  by  a  French  chemist  who  advocates 
the  coating  of  the  bodies  of  the  dead  with  impervious 
platings  of  gold,  silver,  or  copper,  as  a  means  of  preserv- 
ing them.  He  even  suggested  making  statues  in  this  way. 
Copper  has  been  deposited  upon  fabrics  and  upon  glass, 
and  is  almost  invariably  applied  to  the  carbons  of  arc 
lights. 

The  electrolytic  refining  of  copper,  for  the  purpose  of 
obtaining  the  metal  in  a  chemically  pure  state,  is  largely 
carried  on  in  Europe.  The  Keith  process  of  refining  lead 
is  utilized,  we  believe,  in  this  country  only.  The  precious 
metals  are  commonly  separated  in  the  electrolytic  bath  by 
combining  them  with  copper  to  form  an  anode  and  then 


198  THE  AGE   OF  ELECTRICITY. 

electrically  depositing  the  copper,  leaving  the  gold  and 
silver  as  a  residuum. 

A  curious  application  of  electroplating  is  in  the  manu- 
facture of  the  so-called  compound  telegraph-wire,  which 
consists  of  a  central  wire  of  steel  covered  with  a  coating 
of  copper.  This  coating  is  deposited  upon  the  steel  by 
galvanic  action,  while  the  wire  is  drawn  continuously 
through  a  long  trough  containing  the  solution.  A  wire 
thus  made  is  found  to  offer  much  less  resistance  to  the 
current  than  an  ordinary  iron  wire. 

Up  to  within  a  few  years,  the  use  of  electricity  for 
actual  work,  such  as  lighting  or  driving  motors,  has  been 
attended  with  a  great  drawback,  almost  as  important  as 
the  high  cost  of  generating  the  current ;  and  that  is,  it 
has  been  necessary  to  make  the  electricity  as  it  is  needed. 
We  can  store  water  in  a  reservoir,  and  use  it  to  drive  a 
wheel  at  one  time  as  well  as  another.  We  make  gas  dur- 
ing the  day,  and  store  it  in  huge  gasometers  from  which 
a  supply  is  drawn  at  night.  But  with  electricity  it  is 
necessary  to  keep  a  constant  current  flowing  through 
the  conductor,  equal  to  meeting  all  likely  needs,  whether 
it  is  actually  utilized  or  not.  Of  course  this  involves 
continual  expense,  unremitting  wear  of  machinery,  and 
a  great  deal  of  additional  apparatus  ready  to  take  the 
place  of  any  thing  which  may  break  down  or  need  re- 
pair. Inasmuch,  also,  as  the  hours  of  the  night  when 
lights  are  needed  are  few,  it  is  necessary  to  have  very 
powerful  machinery,  capable  of  supplying  a  great  deal  of 
electricity  in  a  short  time.  The  reader  can  easily  imagine 
how  much  greater  the  cost  of  gas  would  be  if  all  of  it 
had  to  be  made  between  the  hours  of  G  P.M.  and  midnight, 
instead  of  its  being  produced  as  it  is,  throughout  the  day. 
In  fact,  at  the  present  time  central  stations  for  the  supply 


ELECTROLYSIS.  199 

of  electricity  from  dynamos  employ  their  capital  fruitfully 
only  about  six  hours  in  the  twenty-four. 

The  question  of  how  to  store  electricity  so  that  we  can 
generate  it  at  one  time,  and  use  it  at  another,  is  therefore 
of  very  great  moment.  We  know,  however,  that  electri- 
city is  not  a  thing  capable  of  storage,  any  more  than  it  is 
a  thing  capable  of  being  burned  in  a  lamp.  The  water 
which  in  falling  drives  a  wheel  is  not  consumed :  simply 
its  energy  is  expended.  If  we  go  a  step  farther,  and 
cause  the  wheel  thus  driven  to  wind  up  a  spring,  or  lift  a 
weight,  we  know  that  we  can  keep  the  spring  wound  up, 
or  the  weight  in  its  lifted  position,  as  long  as  we  choose  ; 
and  that  when  we  release  the  spring,  or  drop  the  weight, 
then  we  can  use  the  energy  thus  stored.  So  that  we  are 
not  to  conceive  of  the  idea  of  pouring  an  electrical  fluid 
into  something,  and  keeping  it  there  ;  but  of  causing  the 
energy  which  exists  in  the  form  we  know  as  electricity,  to 
become  stored,  just  as  the  energy  of  the  water  becomes 
stored  in  the  wound-up  spring  or  lifted  weight.  There  is, 
therefore,  no  such  thing  as  storage  of  electricity.  What 
is  really  done  is  the  changing  of  the  electrical  energy  from 
the  active  condition  to  the  potential  condition,  —  from  the 
state  in  which  it  may  be  doing  work,  to  the  state  in  which 
it  is  not  doing  work  but  is  capable  of  so  doing. 

We  have  already  found  that  if  we  plunge  the  ends  of 
two  wires  leading  from  a  galvanic  cell  into  water,  —  or, 
better,  dilute  sulphuric  acid,  —  bubbles  of  gas  will  appear 
upon  the  immersed  wires,  —  hydrogen  at  the  wire  by  which 
the  current  leaves,  oxygen  at  the  wire  by  which  it  enters. 
This  experiment  is  usually  shown  by  means  of  the  appa- 
ratus shown  in  Fig.  91.  This  consists  of  a  glass  vessel 
(V)  containing  water,  and  also  two  glass  test-tubes  (AB) 
inverted  over  a  pair  of  platinum  plates  projecting  up  from 
the  bottom  of  the  cell  or  vessel.  These  plates  are  con- 


200  THE  AGE  OF  ELECTRICITY. 

nected  by  wires  to  the  poles  of  the  voltaic  battery  (O),  as 
shown  ;  and  therefore  they  act  as  electrodes,  and  pass  the 
current  from  the  battery  through  the  water.  Now,  as  the 
water  is  decomposed,  the  hydrogen  gas  is  found  to  collect 
on  the  cathode,  by  which  the  current  is  supposed  to  leave 
the  water,  while  the  oxygen  collects  on  the  anode,  by  which 
the  current  is  believed  to  enter  the  water  ;  and  as  the  gases 
are  lighter  than  the  water,  they  rise  into  the  upper  ends  of 
the  tubes.  The  volume  of  hydrogen  at  the  cathode  is 


A  B 


Fig.  91. 

always  twice  the  volume  of  oxygen  at  the  anode,  and  this 
agrees  with  the  known  constitution  of  water.  Further,  the 
quantity  of  water  decomposed  in  a  given  time  is  propor- 
tional to  the  strength  of  the  electric  current ;  and  hence,  if 
the  tubes  are  graduated  to  show  the  volume  of  gases  col- 
lected in  them,  the  instrument  becomes  a  voltameter,  or 
current-measurer.  Faraday  arranged  the  apparatus  in  the 
form  shown  in  Fig.  92,  so  that  the  gas  could  easily  be  col- 
lected and  measured.  Here  two  small  platinum  plates  dip 
in  the  acidulated  water,  and  are  connected  to  wires  which 


ELECTROLYSIS. 


201 


pass  up  through  the  cork  of  the  bottle :  binding-screws 
are  attached  to  the  upper  ends  of  these  wires,  and  a  glass 
tube  fixed  into  the  cork  serves  to  discharge  the  gas  formed 
within.  When  the  binding-screws  are  connected  to  the 
poles  of  a  battery,  the  water  in  the  bottle  is  decomposed, 
and  the  hydrogen  and  oxygen  rise  to  the  surface. 

In  this  voltameter  we  have  two  plates  and  a  liquid  in  a 
suitable  vessel.     If  one  of  these  plates  were  zinc,  and  the 
other  copper,  we  know  that  the  zinc  would  be  attacked  by 
the    acidulated    water, 
and    the    apparatus 
would    at    once    be    a 
galvanic    cell    capable 
of    yielding    its    own 
current.     But  here  the 
plates  are  both  of  the 
same   material,    im- 
mersed in  one  liquid ; 
and   hence  one  is  not 
more  attacked  than  the 
other,  and  the  arrange- 
ment cannot  act  as   a 
galvanic  cell. 

When,  however,  the  electric  current  from  another  bat- 
tery is  sent  into  the  voltameter,  then  its  plates  respectively 
yield,  as  we  have  seen,  hydrogen  and  oxygen ;  and  these 
gases,  in  fact,  coat  the  plates.  Now  they  have  become 
different.  Hydrogen  and  oxygen  form  a  galvanic  pair 
by  themselves  ;  and  as  soon  as  the  voltameter  is  discon- 
nected from  its  charging  battery,  and  its  wires  brought 
into  contact,  a  current  is  set  up  through  that  wire,  which 
goes  from  the  hydrogen  to  the  oxygen  within  the  liquid. 

It  will  be  remembered,  that,  in  referring  to  the  so-called 
polarization  of  the  primary  form  of  the  galvanic  battery, 


Fig.  92. 


202 


THE  AGE  OF  ELECTRICITY. 


Balttty 

Fig.  93. 


we  noted  that  after  the  hydrogen  had  formed  on  the  un- 
attacked  element,  a  current  occurred  from  the  hydrogen 
to  the  zinc,  which  ran  opposite  to  and  so  greatly  weakened 
or  destroyed  the  original  current.  In  the  voltameter  there 
is  a  like  action,  and  the  current  yielded  by  the  voltameter 
is  in  the  reverse  direction  to  that  of 
the  battery  current  which  charged  it. 
Let  us  fix  this  with  a  diagram  (Fig. 
93).  Here  we  have  first  the  primary 
cell,  with  its  wires  joined.  The  cur- 
rent goes  in  the  liquid  from  zinc  to 
carbon,  and  thence  back  by  the  wire  to 
the  zinc,  the  arrows  showing  the  direc- 
tion. Next,  we  connect  the  cell  to  the 
voltameter  (Fig.  94) .  Here  the  current  goes  from  the  car- 
bon to  one  plate  of  the  voltameter,  and  produces  oxygen 
thereon  ;  then  through  the  liquid  to  the  other  voltameter 
plate,  where  hydrogen  is  generated  ;  then  back  to  the  zinc, 
and  so  through  the  cell  to  the  carbon  again.  Now  dis- 
connect the  voltame- 
ter, and  join  its  wires 
(Fig.  95).  Then  the 
current  goes  in  the 
liquid  from  the  hy- 
drogen to  the  oxy- 
gen, and  then  by  the 
wire  back  to  the  hy- 
drogen. Compare 
the  direction  of  this 
current  as  indicated  by  the  arrows,  with  the  direction  of 
the  current  in  the  battery  cell,  similarly  indicated,  and  it 
will  be  seen  that  the  currents  move  in  opposite  directions. 
We  have  now  accomplished  a  very  important  result. 
That  is,  by  the  action  of  an  electric  current  we  have  made 


Fig.  94. 


ELECTROLYSIS. 


203 


a  contrivance  into  a  galvanic  cell  which  before  was  not 
one  ;  or,  to  put  it  in  another  way,  we  have  led  a  current 
into  something  from  which,  after  the  source  of  supply  is 
wholly  disconnected,  we  can  get  a  current  out.  This 
is  electrical  storage  —  the  misuse  of  the  term  aside.  It 
looks  as  if  we  had  poured  the  electricity  into  the  volta- 
meter, just  as  we  might  pour  in  the  liquid,  and  afterwards 
drawn  out  the  one  as  we  might  the  other. 

The  voltameter  reversed  as  above  described  yields, 
however,  only  a  momentary  current ;  for  very  little  of  the 
gases  stay  on  the  plates,  the  greater  portion  mixing  and 
rising  as  we  have  seen.  The  gases  do  not  act  on  either 
plate,  because  the  material  of  the  latter, 
platinum,  is  not  easily  attacked. 

The  first  secondary  battery  was  de- 
vised by  Ritter  of  Jena,  very  shortly 
after  the  invention  of  the  voltaic  pile. 
It  had  been  found,  that,  if  an  oblong 
slip  of  wet  paper  have  its  extremities  in 
contact  with  the  poles  of  the  pile,  each 
half  of  the  slip  will  be  electrified  ;  and 
if  it  be  removed  from  contact  with  the  pile,  by  a  rod  of 
glass  or  other  non-conductor,  its  electric  state  will  continue. 
This  was  observed  by  Volta,  and,  according  to  Dr.  Lardner 
(writing  in  1841),  "  was  the  means  of  suggesting  to  Ritter 
the  idea  of  his  secondary  pile  ;  which  consisted  of  a  series 
of  disks  of  a  single  metal,  alternated  with  cloth  or  card 
moistened  in  a  liquid  by  which  the  metal  would  not  be 
affected  chemically.  If  such  a  pile  have  its  extremities 
put  in  connection,  by  conducting  substances,  with  the 
poles  of  an  insulated  voltaic  pile,  it  will  receive  a  charge 
of  electricity  in  a  manner  similar  to  the  band  of  wet  paper, 
—  one  half  taking  a  positive  and  the  other  a  negative 
charge  ;  and,  after  its  connection  with  the  primary  pile 


204 


THE  AGE  OF  ELECTRICITY. 


has  been  broken,  it  will  retain  the  charge  it  has  thus  re- 
ceived. The  secondary  pile,  while  it  retains  its  charge, 
produces  the  same  physiological  and  chemical  effects  as 
the  voltaic  apparatus." 

In  1859  M.  Gaston  Plante  made  a  secondary  cell  based 
upon  the  principles  above  briefly  sketched.  Instead  of 
plates  of  platinum  he  used  plates  of 
lead,  rolled  as  shown  in  Fig.  90.  The 
consequence  was,  that,  when  the  cur- 
rent passed  through  these,  the  oxygen 
produced  at  one  plate  combined  with 
the  metal,  and  deposited  lead  oxide ; 
the  hydrogen  as  before  remained  free 
on  the  other  plate.  Thus  he  produced 
a  cell  in  which,  after  the  charging  cur- 
rent was  removed,  were  elements  of  lead 
and  lead  oxide.  These  being  connected 
yielded  a  current,  but,  however,  for  a 
short  time,  because  but  very  little  of  the 
oxide  was  produced,  —  a  mere  film  on 
the  surface.  Plante"  thereupon  devised 
his  so-called  "forming"  process,  which 
consisted  in  first  charging  his  plates, 
then  discharging,  then  charging  again 
with  the  battery  current  reversed,  and 
so  on,  increasing  intervals  of  rest  being  left  between  the 
operations  ;  until  finally  he  produced,  through  the  repeated 
oxidations  and  subsequent  reductions  of  the  oxidized  ma- 
terial to  a  metallic  state,  very  porous  or  spongy  plates. 
These,  by  reason  of  their  porosity,  exposed  a  very  large 
surface  to  the  oxidizing  action  of  the  current,  so  that  the 
result  was  as  if  he  had  charged  a  plate  of  great  superficial 
area. 

As  we  have  already  shown,  when  batteries  are  connected 


Fig.  96. 


ELECTROLYSIS. 


205 


in  multiple  arc,  —  that  is,  all  the  zinc  plates  together, 
and  all  the  copper  plates  together,  —  then  the  plates  of 
each  kind  act  as  one  large  plate,  the  surfaces  of  all  being 
added  together.  Plante  found  that  if  he  charged  a  num- 
ber of  secondary  cells  connected  in  this  way,  and,  after 
charging,  if  he  arranged  his  cells  in  series,  —  that  is,  the 
positive  plate  of  one  con- 
nected to  the  negative  plate 
of  the  next,  and  so  on,  —  he 
could  obtain  very  powerful 
currents  for  short  periods  of 
time. 

In  1880  M.  Camille  Faure 
covered  Plante"  's  lead  plates 
with  red  lead,  and  then  put 
them  in  little  flannel  jackets. 
The  peculiarity  of  the  red 
lead  is,  that,  on  sending  a 
current  through  it,  it  is  easily 
changed  into  spongy  lead  ;  so 
that,  instead  of  the  ' '  form- 
ing "  operation  taking  weeks 
and  months,  it  can  be  done 
in  a  few  days  or  even  hours. 
This  discovery  apparently  re- 
moved the  chief  obstacle  to 
Planters  cells  becoming  of 

commercial  value  ;    and  when  it  was  announced,  it  was 
hailed  as  an  extraordinary  advance. 

Since  1880  a  great  many  patents  have  been  obtained 
for  secondary  batteries,  and  they  now  exist  in  many  forms. 
An  example  of  the  Faure  type  is  Reynier's  cell,  which  is 
represented  in  Fig.  97.  In  a  glass  jar  are  placed  two 
spirals  of  rolled  lead  plate,  against  which  the  red  lead  is 


Fig.  97. 


206  THE  AGE   OF  ELECTRICITY. 

held  by  serge  instead  of  the  felt  or  flannel  which  Faure 
adopted.  Mainly,  however,  the  efforts  of  inventors  have 
been  directed  to  reducing  the  weight  of  the  cells,  and  to 
devising  new  ways  of  holding  the  red  lead  on  the  plates. 
Brush  packs  his  red  lead  or  other  active  material  in  a 
frame  of  cast  lead  containing  slots,  cells,  or  openings. 
Sellon  also  makes  a  plate  with  receptacles  for  containing 
and  holding  the  active  material. 

The  storage-battery  at  the  present  time  is  simply  a  sub- 
ject for  further  research  and  invention.  No  form  of  it 
exists  in  which  grave  defects  are  not  present.  The  value 
and  efficiency  of  many  of  the  cells  offered  in  the  market 
have  been  over-estimated,  and  often  greatly  misunder- 
stood. None  are  more  eager  to  grasp  at  possible  im- 
provements than  those  who  to-day  most  loudly  vaunt  the 
great  merit  of  their  own  particular  advertised  contriv- 
ances ;  this  not  infrequently  in  the  hope  that  the  large 
amounts  of  capital  already  risked  may  by  some  stroke  of 
good  fortune  be  saved  from  loss. 

The  commonest  defects  of  the  storage-cell  are  ' '  nee- 
dling," "buckling,"  and  "disintegration."  Needling  is 
the  formation  of  the  so-called  "lead  tree,"  —  fine  spiculae 
of  metal  between  the  electrodes,  which  causes  short  cir- 
cuiting and  rapid  waste  of  current.  Buckling  is  the  defor- 
mation or  bending  of  the  plates  themselves,  whereby  one 
plate  often  makes  contact  with  another,  and  short  circuit- 
ing again  follows.  Disintegration  and  buckling  also  are 
usually  due  to  chemical  changes  in  the  electrodes.  The 
plates,  disintegrating  in  time,  drop  to  pieces.  Besides 
these  difficulties,  certain  solutions  cause  very  high  internal 
resistance  in  the  cell ;  and  there  are  a  variety  of  other 
disadvantages. 

One  of  the  best  forms  of  storage  battery  is  that  devised 
by  Mr.  Willard  E.  Case,  in  which  he  uses  a  neutral  liquid, 


ELECTROLYSIS.  207 

from  which  he  deposits  metal  on  one  electrode  while 
peroxidizing  the  other. 

Mr.  Case's  investigations  in  the  storage-battery  have 
led  him  to  the  remarkable  discovery  that  heat  can  be 
directly  converted  into  electricity  in  the  galvanic  cell.  He 
places  in  his  cell  an  electrode  of  tin,  an  electrode  of  car- 
bon, and  a  liquid  which  at  ordinary  temperature  will  not 
attack  either  electrode.  Therefore  no  current  is  yielded. 
But  as  soon  as  the  liquid  is  warmed,  —  and  to  do  this  the 
cell,  which  is  hermetically  sealed  once  for  all,  is  merely  put 
into  hot  water,  —  chlorine  is  set  free  from  the  liquid,  and 
attacks  the  tin.  Then  the  current  starts,  and  continues 
until  all  the  tin  is  converted  into  chloride.  Now,  if  the 
cell  be  allowed  to  cool,  the  chlorine  releases  the  tin,  and 
returns  to  the  liquid  ;  and  so  the  cell  regains  its  original 
state.  The  chlorine,  in  fact,  is  a  chemical  pendulum, 
swinging  from  liquid  to  tin,  and  from  tin  to  liquid,  as  often 
as  the  heat  is  applied  and  removed.  Of  course  the  cell 
lasts  indefinitely  ;  theoretically,  forever.  No  material  is 
used  up  in  it.  The  temperature  is  never  above  that  of 
boiling  water.  Its  electro-motive  force  is  about  one-quarter 
volt. 

In  one  sense  this  cell  may  be  regarded  as  a  heat-storage 
battery :  it  is  really  a  wonderfully  efficient  heat-engine. 
It  is  not  merely  a  most  beautiful  and  ingenious  illustration 
of  the  correlation  and  interconvertibility  of  the  natural 
forces,  but  an  advance  apparently  destined  to  be  of  the 
highest  practical  value. 

Electrolysis  has  been  applied  to  the  rectification  of 
alcohols,  the  improvement  of  wines,  and  to  the  deposition 
of  aniline  dyes. 


208  THE  AGE  OF  ELECTRICITY. 


CHAPTER  XI. 

THE    ELECTRIC    TELEGRAPH. 

THE  earliest  suggestion  of  the  electric  telegraph  appears 
in  the  Prohisiones  Academics  of  Strada,  an  Italian  Jesuit, 
who  in  1617  spoke  of  "  the  instantaneous  transmission 
of  thoughts  and  words,  between  two  individuals,  over  an 
indefinite  space,"  caused  by  a  species  of  loadstone,  which 
possesses  such  virtue,-  that,  if  two  needles  be  touched 
with  it,  and  then  balanced  on  separate  pivots,  and  the 
one  turned  in  a  particular  direction,  the  other  will  sympa- 
thetically move  parallel  to  it.  These  needles  were  to  be 
poised  and  mounted  on  a  dial  with  the  letters  of  the 
alphabet  around. 

In  "  The  Spectator  "  of  1712,  Addison  proposes  the 
sending  of  love-letters  in  this  way.  In  187G,  when  the 
speaking  telephone  first  appeared,  and  before  many  peo- 
ple had  any  conception  of  its  extraordinary  capabilities, 
4 'The  New- York  Tribune"  suggested  that  its  principal 
value  might  lie  in  the  fact  that  lovers  and  diplomatists 
could  thus  secretly  converse  ;  and  thus  history  repeated 
itself. 

There  was  no  lack  of  experiments  upon  electric  tele- 
graphs during  the  last  century.  All  of  them  depended 
upon  the  idea  of  sending  the  charge  of  static  or  frictional 
electricity  through  one  or  more  wires  ;  for  the  galvanic 
battery  had  not  yet  been  invented. 


THE  ELECTRIC  TELEGRAPH.  209 

In  1729  Gray  and  Wheeler  produced  motion  in  light 
bodies  at  a  distance  of  666  feet.  In  1747  Dr.  Watson, 
in  the  presence  of  many  scientific  persons,  transmitted 
electricity  through  twenty-eight  hundred  feet  of  wire  and 
eight  thousand  feet  of  water,  thus  making  use  of  the 
earth  circuit.  In  the  following  year  Franklin  fired  spirits 
on  one  side  of  the  Schuylkill  River,  by  the  discharge  from 
an  electrical  battery  on  the  opposite  bank. 

Then  followed  a  curious  series  of  endeavors  to  adapt 
the  results  of  the  experiments  of  Watson  and  Franklin 
to  every-day  use.  The  first  practicable  form  of  electric 
telegraph  was  described  in  "The  Scots  Magazine"  in 
1753,  in  an  anonymous  communication  over  the  initials 
C.  M.  The  article  was  entitled  "  An  Expeditious  Method 
of  conveying  Intelligence."  It  was  proposed  to  extend 
wires,  equal  in  number  to  the  letters  of  the  alphabet, 
between  two  distant  places ;  support  them  at  intervals  on 
glass  fixed  to  solid  bodies ;  let  each  wire  terminate  in  a 
ball ;  place  beneath  each  ball  a  shred  of  paper  on  which 
the  corresponding  letter  of  the  alphabet  has  been  printed. 
Bring  the  farther  end  of  the  first  wire  into  contact  with 
an  excited  glass  tube,  and  the  paper  A  will  instantly  rise 
to  the  first  ball.  Thus  the  whole  alphabet  may  be  repre- 
sented. Here,  evidently,  was  the  idea  of  complete  insu- 
lation of  the  conducting  wire,  and  at  the  distant  end  the 
production  of  a  signal  which  should  be  either  visible  or 
audible*;  for  the  inventor  also  proposed  a  series  of  bells, 
differing  in  tone  from  A  to  Z,  instead  of  the  paper. 

Very  little  is  known  of  the  inventor.  Sir  David  Brews- 
ter  asserts  that  his  name  was  Charles  Morrison.  It  is 
frequently  quoted  as  Charles  Marshall.  In  fact,  about 
the  only  definite  information  ever  obtained  was  from  a 
very  old  Scotch  lady  who  remembered  a  "very  clever 
man,  of  obscure  position,  '  who  could  make  lichtnin'  write 


210  THE  AGE  OF  ELECTRICITY. 

an'  speak,  and  who  could  licht  a  room  wi'  coal  reek  '  (i.e., 
coal  smoke)."  That  a  great  genius  thus  became  lost  to 
the  world,  can  hardly  be  doubted  ;  for  here  was  a  man 
who  had  seen  farther  into  the  mysteries  of  electricity  than 
Franklin  himself.  We  can  easily  imagine  his  fate.  Being 
ahead  of  his  time,  his  neighbors  —  those  typical  neighbors 
of  the  inventor,  who  mend  the  adage  to  make  the  prophet 
not  only  without  honor,  but  with  positive  dishonor,  in  his 
own  country  —  called  him  a  visionary  and  a  madman. 
There  is  more  true  pathos  in  the  many  stories  of  the 
stout  hearts  thus  broken,  than  in  all  the  romantic  vicissi- 
tudes of  the  Abelards  and  the  Heloises  since  the  Flood. 

For  several  years  following,  little  advance  was  made. 
Lomond  in  1787  proposed  a  single  wire  and  a  pith-ball 
electrometer.  Reizen  in  1794  contrived  a  telegraph  like 
Marshall's,  but  added  letters  of  the  alphabet  cut  out  in 
pieces  of  tin-foil  and  rendered  visible  by  sparks.  Cavallo 
went  back  to  the  single-wire  idea,  and  used  sparks  to 
designate  the  various  signals,  and  an  explosion  of  gas 
to  alarm  the  operator. 

Then  came  a  lapse  of  some  fifteen  years,  and  mean- 
while the  voltaic  pile  was  discovered.  When  the  inventors 
came  to  apply  this  to  telegraphy,  they  went  to  work  in 
the  same  old  way.  Soemmering,  in  1809,  used  as  many 
wires  as  there  were  signals,  but  varied  these  by  producing 
them  by  the  decomposition  of  water.  The  battery  not 
proving  very  successful,  Mr.  (afterwards  Sir)  Francis 
Ronalds  abandoned  it  in  favor  of  the  more  intense  dis- 
charge of  the  Leyden-jar ;  and  arranged  a  pith-ball  elec- 
trometer at  the  end  of  his  line,  wherewith  he  made  his 
signals. 

This  was  done  in  1816.  Seventy  years  had  elapsed 
since  Watson's  experiment  proving  the  possibility  of 
transmitting  the  electrical  discharge  over  long  distances. 


THE  ELECTRIC  TELEGRAPH.  211 

Yet  the  actual  advance  made  toward  a  practicable  and 
useful  electric  telegraph  had  been  scarcely  any  thing. 
The  discharge  could  be  sent  over  one  wire  ;  and  repeated 
sparks,  or  movements  of  a  pith-ball,  would  indicate  sig- 
nals—  the  weather  permitting.  It  could  be  sent  over 
twenty-six  wires,  and  each  wire  might  then  make  its  own 
signal.  The  signals  might  be  produced  by  the  decomposi- 
tion of  water  or  salts,  or  by  explosions,  or  illuminations  of 
tin-foil  letters.  It  is  not  surprising  that  the  Lords  of  the 
Admiralty  in  1813,  after  considering  one  of  the  many  plans 
submitted  to  them,  said  that  as  the  war  was  not  over,  and 
money  scarce,  they  thought  best  not  to  carry  it  into  effect. 
Oersted's  grand  discovery  came  in  1819,  and  in  1820 
Ampere  devised  the  galvanometer.  He  was  quick  to  see, 
that,  if  the  current  could  deflect  the  needle  at  a  short 
distance,  there  was  a  possibility  of  its  doing  the  same  at 
a  long  distance ;  but  he  was  unable,  apparently,  to  break 
away  from  the  multiple- wire  idea.  He,  too,  proposed  the 
use  of  as  many  wires  as  letters  or  signals  to  be  indicated. 
That  happened  in  the  same  year  that  the  electro-magnet 
was  invented  by  Arago.  Looking  back  on  these  proceed- 
ings now,  it  seems  as  if  all  these  philosophers  and  inventors 
of  Europe  were  groping  through  a  labyrinth,  one  following 
the  blind  lead  of  the  static  charge,  and  another  that  of 
the  multiple  wire ;  some  rejecting  the  very  means  which 
would  conduct  them  to  a  successful  ending,  in  the  belief 
that  they  were  merely  obstacles  ;  others  clinging  to  obsta- 
cles, in  the  belief  that  they  were  clews.  In  1820  the 
actual  elements  of  the  telegraph  of  to-day  were  in  their 
grasp.  They  had  the  electro-magnet,  the  conducting  wire, 
and  the  galvanic  battery ;  but  no  eyes  to  see  what  could 
be  accomplished  by  these  means.  So  far  as  they  knew, 
no  battery  could  send  its  current  over  a  long  line,  and 
magnetize  something  at  the  other  end. 


212  THE  AGE  OF  ELECTRICITY. 

The  European  philosophers  kept  on  groping.  At  the 
end  of  five  years,  one  of  them  reached  an  obstacle  which 
he  made  up  his  mind  was  so  entirely  insurmountable, 
that  it  rendered  the  electric  telegraph  an  impossibility 
for  all  future  time.  This  was  Mr.  Peter  Barlow,  fellow 
of  the  Koyal  Society,  who  had  encountered  the  question 
whether  the  lengthening  of  the  conducting  wire  would  pro- 
duce any  effect  in  diminishing  the  energy  of  the  current 
transmitted,  and  had  undertaken  to  resolve  the  problem. 
Here  is  his  conclusion  in  his  own  words :  — 

"  It  had  been  said  that  the  electric  fluid  from  a  common 
electrical  battery  had  been  transmitted  through  a  wire  four 
miles  in  length,  without  any  sensible  diminution  of  effect, 
and  to  every  appearance  instantaneously ;  and  if  this 
should  be  found  to  be  the  case  with  the  galvanic  current, 
then  no  question  could  be  entertained  of  the  practicability 
and  utility  of  the  suggestion  before  adverted  to.  I  was 
therefore  induced  to  make  the  trial,  but  I  found  such  a  con- 
siderable diminution  icith  only  two  hundred  feet  of  wire,  as 
at  once  to  convince  me  of  the  impracticability  of  the  scheme." 

Barlow's  conclusion  would  possess  no  especial  interest 
now,  other  than  that  which  would  necessarily  attach  to  the 
views  of  any  eminent  observer  of  the  period,  were  it  not 
for  the  singular  fact,  that  the  circumstance  of  its  publica- 
tion had  probably  more  to  do  with  the  later  successful 
realization  of  the  electric  telegraph,  than  any  other  occur- 
rence in  the  history  of  the  invention.  The  year  following 
the  announcement  of  Barlow's  conclusions,  a  young  grad- 
uate of  the  Albany  (N.Y.)  Academy  —  byname  Joseph 
Henry  —  was  appointed  to  the  professorship  of  mathemat- 
ics in  that  institution.  Henry  there  began  the  series  of 
scientific  investigations  which  is  now  historic ;  thus  bril- 
liantly opening  a  career  which  at  its  end  found  him  easily 
the  first  among  American  scientists. 


THE  ELECTRIC  TELEGRAPH.  213 

Up  to  that  time,  electro-magnets  had  been  made  with 
a  single  coil  of  naked  wire  wound  spirally  around  the 
core,  with  large  intervals  between  the  strands.  The  core 
was  insulated  as  a  whole  :  the  wire  was  not  insulated  at 
all.  Professor  Schweigger,  who  had  previously  invented 
the  multiplying  galvanometer,  had  covered  his  wires  with 
silk.  Henry  followed  this  idea,  and,  instead  of  a  single 
coil  of  wire,  used  several.  He  says,  "  These  experiments 
conclusively  proved  that  a  great  development  of  mag- 
netism could  be  effected  by  a  very  small  galvanic  ele- 
ment ;  and,  also,  that  the  power  of  the  coil  was  materially 
increased  by  multiplying  the  number  of  wires,  without 
increasing  the  length  of  each."  He  also  found  that  he 
could  obtain  stronger  results  with  the  wires  so  wound  that 
the  pitch  of  one  spiral  should  be  the  reverse  of  that  of 
the  spiral  beneath  it.  And  lastly  he  discovered  that  a 
magnet  with  a  long  fine-wire  coil  must  be  worked  by  a 
battery  having  high  electro-motive  force,  composed  of 
a  large  number  of  cells  in  series,  when  a  distant  effect 
was  required  ;  and  that  the  greatest  dynamic  effect  close 
at  hand  is  produced  by  a  battery  of  a  very  few  cells  of 
large  surface,  combined  with  a  coil  or  coils  of  short  thick 
wire  around  the  magnet. 

"  But,  be  this  as  it  may,"  says  Henry,  after  describing 
his  discoveries  as  above  very  briefly  outlined,  "the  fact 
that  the  magnetic  action  of  a  current  from  a  trough  is  at 
least  not  sensibly  diminished  by  passing  through  a  long 
wire  is  directly  applicable  to  Mr.  Barlow's  project  of  form- 
ing an  electro-magnetic  telegraph,  and  also  of  material 
consequence  in  the  construction  of  the  galvanic  coil." 

Barlow  had  said  that  the  gentle  current  of  the  galvanic 
battery  became  so  weakened,  after  traversing  two  hundred 
feet  of  wire,  that  it  was  idle  to  consider  the  possibility  of 
making  it  pass  over  even  a  mile  of  conductor  and  thec 


214  THE  AGE  OF  ELECTRICITY. 

affect  a  magnet.  Henry's  reply  was  to  point  out  that  the 
trouble  lay  in  the  way  Barlow's  magnet  was  made.  The 
resistance  of  the  line  weakened  the  current.  Start,  then, 
with  a  strong  current,  —  an  "•  intensity  current," — Henry 
said :  let  the  line  resistance  weaken  it,  but  make  the  mag- 
net so  that  the  diminished  current  will  exercise  its  full 
effect.  Instead  of  using  one  short  coil,  through  which 
the  current  can  easily  slip,  and  do  nothing,  make  a  coil  of 
many  turns  ;  that  increases  the  magnetic  field :  make  it 
of  fine  wire,  and  of  higher  resistance.  And  then,  to  prove 
the  truth  of  his  discovery,  Henry  put  up  the  first  electro- 
magnetic telegraph  ever  constructed.  In  the  academy  at 
Albany,  in  1831,  he  suspended  1,060  feet  of  bell-wire, 
with  a  battery  at  one  end  and  one  of  his  magnets  at  the 
other ;  and  he  made  that  magnet  attract  and  release  its 
armature.  The  armature  struck  a  bell,  and  so  made  the 
signals. 

Annihilating  distance  in  this  way  was  only  one  part  of 
Henry's  discovery.  He  had  also  found,  that,  to  obtain 
the  greatest  dynamic  effect  close  at  hand,  the  battery 
should  be  composed  of  a  very  few  cells  of  large  surface, 
combined  with  a  coil  or  coils  of  short  coarse  wire  around 
the  magnet,  —  conditions  just  the  reverse  of  those  neces- 
sary when  the  magnet  was  to  be  worked  at  a  distance. 
Now,  he  argued,  suppose  the  magnet  with  the  coarse  short 
coil,  and  the  large-surface  battery,  be  put  at  the  receiving- 
station  ;  and  the  current  coming  over  the  line  be  used 
simply  to  make  and  break  the  circuit  of  that  local  battery. 
That  is  a  very  small  thing  to  do,  — very  different  from  mak- 
ing the  tired  current,  so  to  speak,  work  a  lot  of  signalling 
or  recording  mechanism.  The  local  battery  and  magnet 
then  do  the  hard  labor ;  the  current  coming  over  the  line 
merely  controls  the  force  :  or,  in  other  words,  instead  of  an 
engine  driven  by  power  coming  from  a  very  long  distance, 


THE  ELECTRIC   TELEGRAPH.  215 

and  wasted  greatly  on  its  way,  we  have  one  operated  by 
power  immediately  at  hand,  but  controlled  from  a  point 
miles  away.  This  is  the  principle  of  the  telegraphic 
"  relay."  In  1835  Henry  worked  a  telegraph-line  in  that 
way  at  Princeton.  And  thus  the  electro-magnetic  tele- 
graph was  completely  invented  and  demonstrated.  There 
was  nothing  left  to  do,  but  to  put  up  the  posts,  string  the 
lines,  and  attach  the  instruments.  The  question  asked 
thousands  of  years  before  by  the  prophet,  "Canst  thou 
send  lightnings,  that  they  may  go,  and  say  unto  thee, 
Here  we  are?"  Henry  had  answered  in  the  affirmative. 
It  remained  for  other  men,  following  his  example,  to  go 
and  do  likewise. 

It  is,  as  we  have  said,  a  common  misfortune  of  invent- 
ors, to  be  ahead  of  the  times  in  which  they  live  ;  and  this 
was  Henry's  experience.  It  is  true  that  he  contributed  to 
the  result  himself,  by  refusing  to  patent  his  ideas,  and  so 
hiding  his  light  under  a  bushel.  But  the  fact  none  the 
less  remains,  that  here  was  a  discovery  not  merely  of 
transcendent  importance,  but  one  which  the  world  had 
been  eagerly  trying  to  make  for  years  ;  and  yet,  when  it 
was  achieved,  no  one  stood  ready  to  put  it  to  practical 
use.  So  little  was  it  known  or  appreciated,  that  when  on 
April  15,  1837,  the  Secretary  of  the  Treasury,  Hon.  Levi 
Woodbury,  sent  out  a  circular  letter  proposing  inquiries 
on  the  subject  of  a  system  of  telegraphs  for  the  United 
States,  the  Franklin  Institute  of  Philadelphia,  the  leading 
scientific  body  of  the  land,  could  find  nothing  better  to 
recommend  than  the  semaphore,  or  mechanical  telegraph. 
The  report  advocates  the  erection  of  forty  stations  be- 
tween New  York  and  Washington  ;  each  station  being  a 
building  twenty-two  feet  square,  with  a  quadrangular 
pyramidal  roof  on  which  the  swinging  arms  of  the  sema- 
phore were  to  be  mounted.  By  moving  the  arms  into 


216  THE  AGE  OF  ELECTRICITY. 

different  positions,  numbers  and  letters  were  to  be  indi- 
cated, and  the  observer  at  one  station  would  be  enabled  to 
recognize  the  signals  made  at  the  next  station,  some  seven 
miles  away,  by  means  of  a  telescope.  "In  conclusion," 
says  the  report,  ' '  the  committee  would  respectfully  sug- 
gest to  the  Secretary  of  the  Treasury  to  consider  the  pro- 
priety of  causing  two  telegraphs  to  be  erected,  in  which 
careful  experiments  may  be  made  on  all  the  points  which 
bear  upon  the  general  questions  submitted  to  him  by  the 
House  of  Representatives." 

Meanwhile  one  electric  telegraph  had  been  erected  in 
this  country.  This  was  based  on  the  use  of  the  static 
discharge.  It  was  put  up  by  Harrison  Gray  Dyer,  on  a 
race-course  on  Long  Island ;  and  it  is  a  noteworthy  fact, 
that  he  strung  his  wires  on  glass  insulators  upon  trees  and 
poles.  The  electrical  discharge,  after  passing  over  the 
wire,  acted  upon  litmus  paper  to  produce  a  red  mark. 
The  difference  in  time  between  the  sparks  indicated  dif- 
ferent letters,  arranged  in  an  arbitrary  alphabet ;  and  the 
paper  was  moved  by  hand.  This  line  was  used  in  1827- 
28. 

It  will  be  apparent,  therefore,  that,  at  the  time  the  fore- 
going report  was  made  by  the  Franklin  Institute,  both  of 
the  two  known  systems  of  electric  telegraphy  had  been 
practically  tested  in  this  country ;  the  static-discharge 
telegraph  by  Dyer,  and  the  electro-magnetic  telegraph  by 
Henry.  "In  1832,"  says  Henry,  "nothing  remained  to 
be  discovered  in  order  to  reduce  the  proposition  of  the 
electro-magnetic  telegraph  to  practice.  I  had  shown  that 
the  attraction  of  the  armature  could  be  produced  at  any 
distance,  and  had  designed  the  kind  of  a  battery  and  coil 
around  the  magnet  to  be  used  for  this  purpose.  I  had 
also  pointed  out  the  fact  of  the  applicability  of  my  experi- 
ments to  the  electro-magnetic  telegraph."  Five  years 


THE  ELECTRIC   TELEGRAPH.  217 

after  this,  the  learned  scientists  of  the  Franklin  Institute 
offered  to  the  Government  the  services  of  their  committee 
to  experiment,  not  upon  electric  telegraphs,  but  sema- 
phores ! 

Among  the  replies  forwarded  to  the  Secretary  of  the 
Treasury,  in  answer  to  his  circular,  were  three  letters 
signed  Samuel  F.  B.  Morse,  all  advocating  the  establish- 
ment of  an  electro-magnetic  telegraph.  Morse  was  an 
artist  of  some  repute,  but  not  in  any  sense  an  educated 
electrician.  In  the  latter  part  of  the  year  1832,  while  on 
a  homeward  voyage  from  Europe,  he  conceived  the  idea 
of  an  electric  or  electro-chemical  telegraph,  and  devised  a 
system  of  signs  for  letters  to  be  marked  by  the  breaking 
and  closing  of  the  electric  circuit.  Dr.  C.  T.  Jackson  of 
Boston  was  a  passenger  on  the  same  vessel ;  and,  being 
well  versed  in  electricity,  Morse  went  to  him  for  informa- 
tion. It  appears,  however,  that  neither  Morse  nor  Jack- 
son at  that  time  had  conceived  of  any  thing  more  than  an 
electro-chemical  telegraph,  in  which  the  current  might  de- 
compose chemical  compounds  so  as  to  leave  a  permanent 
mark.  Morse's  idea,  from  the  beginning,  seems  to  have 
been  principally  to  make  the  current  record  itself.  In 
1835  Morse  was  appointed  to  a  professorship  in  the  Uni- 
versity of  New  York,  and  then  he  contrived  the  mechani- 
cal arrangement  which  formed  the  basis  for  his  subsequent 
inventions.  This  consisted,  at  the  receiving-station,  of  a 
strip  of  paper  about  half  an  inch  in  breadth,  moved  length- 
wise over  a  roller  by  clock-work.  Above  the  paper  hung 
a  pendulum  which  vibrated  across  the  paper,  and  carried 
at  its  lower  end  a  pencil.  Normally,  as  the  paper  moved 
along,  the  pencil  traced  a  simple  straight  line.  Near  the 
pendulum  was  an  electro-magnet,  the  armature  of  which 
was  attached  to  the  pendulum.  The  electro-magnet  was 
connected  to  the  line  wire.  Whenever  a  current  came 


218  THE  AGE  OF  ELECTRICITY. 

over  the  wire,  the  magnet  was  energized,  and  caused  to 
attract  its  armature,  and  so  cause  the  pencil  to  move 
across  the  paper,  so  that  zigzag  lines  were  produced, 
which  represented  letters,  numbers,  etc. 

Morse  encountered  the  same  trouble  which  all  previous 
experimenters  before  him,  Henry  alone  excepted,  had  met. 
His  current  was  dissipated  before  it  reached  the  end  of 
the  line.  He  then  adopted  the  relay  plan  in  the  spring  of 
1837.  On  Nov.  28,  1837,  Morse  wrote  to  the  Secretary : 
"We  have  procured  several  miles  of  wire,  and  I  am  happy 
to  announce  to  you  that  our  success  has  thus  far  been 
complete.  At  the  distance  of  five  miles,  with  a  common 
Cruikshank's  battery  of  eighty-seven  plates  (4  by  3J  inches 
each  plate),  the  marking  was  as  perfect  on  the  register  as 
in  the  first  instance  of  half  a  mile.  We  have  recently 
added  five  miles  more,  making  in  all  ten  miles,  with  the 
same  result ;  and  we  have  no  doubt  of  its  effecting  a 
similar  result  at  any  distance." 

In  1838  Morse  took  his  apparatus  to  Washington,  and 
exhibited  it  to  Congress  ;  but  that  body,  despite  the  rec- 
ommendations of  its  committees,  took  no  action.  Four 
years  passed  by,  during  which  time  Morse  made  appeal 
after  appeal.  He  was  at  last  successful. 

He  says,  "My  bill  had  indeed  passed  the  House  of 
Representatives,  and  it  was  on  the  calendar  of  the  Senate  ; 
but  the  evening  of  the  last  day  had  commenced  with  more 
than  one  hundred  bills  to  be  considered  and  passed  upon 
before  mine  could  be  reached.  Wearied  out  with  the  anx- 
iety of  suspense,  I  consulted  one  of  my  senatorial  friends. 
He  thought  the  chance  of  reaching  it  to  be  so  small,  that 
he  advised  me  to  consider  it  as  lost,  lu  a  state  of  mind 
which  I  must  leave  you  to  imagine,  I  returned  to  my  lodg- 
ings to  make  preparations  for  returning  home  the  next 
day.  My  funds  were  reduced  to  a  fraction  of  a  dollar. 


THE  ELECTRIC  TELEGRAPH.  219 

In  the  morning,  as  I  was  about  to  sit  clown  to  breakfast, 
the  servant  announced  that  a  young  lady  desired  to  see 
me  in  the  parlor.  It  was  the  daughter  of  my  excellent 
friend  and  college  classmate,  the  Commissioner  of  Patents 
(Henry  L.  Ellsworth).  She  had  called,  she  said,  by  her 
father's  permission,  and  in  the  exuberance  of  her  own 
joy,  to  announce  to  me  the  passage  of  my  telegraph-bill 
at  midnight,  but  a  moment  before  the  Senate's  adjourn- 
ment. This  was  the  turning-point  of  the  telegraph  inven- 
tion in  America.  As  an  appropriate  acknowledgment  for 
the  young  lady's  sympathy  and  kindness,  —  a  sympathy 
which  only  a  woman  can  feel  and  express,  —  I  promised 
that  the  first  despatch  by  the  first  line  of  telegraph  from 
Washington  to  Baltimore  should  be  indited  by  her :  to 
which  she  replied,  'Remember,  now,  I  shall  hold  you 
to  your  word.'  In  about  a  year  from  that  time,  the  line 
was  completed  ;  and,  every  thing  being  prepared,  I  ap- 
prised my  young  friend  of  the  fact.  A  note  from  her 
enclosed  this  despatch  :  '  What  hath  God  wrought.'  These 
were  the  first  words  that  passed  on  the  first  completed 
line  of  electric  wires  in  America." 

Congress  appropriated  thirty  thousand  dollars  for  the 
construction  of  Morse's  experimental  line  between  Wash- 
ington and  Baltimore,  a  distance  of  forty  miles.  It  was 
put  in  operation  in  the  spring  of  1844,  and  was  shown 
without  charge  until  April  1,  1845.  Congress,  during  the 
session  of  1844-45,  made  an  appropriation  of  eight  thou- 
sand dollars  to  keep  it  in  operation  during  the  year ; 
placing  it,  at  the  same  time,  under  the  supervision  of  the 
Postmaster-General.  He  fixed  the  first  tariff  of  charges 
at  one  cent  for  every  four  characters  made  by  or  through 
the  telegraph. 

The  object  of  imposing  a  tariff  was  to  test  the  profita- 
bleness of  the  enterprise.  The  result  of  the  experiment 


220  THE  AGE   OF  ELECTRICITY. 

for  the  four  days  after  April  1  w/is  amusing.  It  was  then 
very  shortly  after  Folk's  inauguration  ;  and  Washington 
was  crowded  with  office-seekers,  of  whom  large  numbers 
came  to  stare  at  the  telegraph  as  one  of  the  sights  of  the 
capital.  On  the  morning  of  April  1,  a  gentleman  walked 
into  the  office,  and  directed  that  the  operation  of  the  con- 
trivance be  exhibited  to  him.  The  operator  said  he  would 
be  pleased  to  do  so,  at  the  regular  charge  of  one  cent  per 
four  characters,  and  it  would  therefore  cost  very  little  for 
the  visitor  to  send  his  name  to  Baltimore,  and  have  it 
telegraphed  back,  or  make  some  other  simple  test.  The 
applicant  said  that  he  did  not  propose  to  pay  any  thing ; 
did  not  wish  to  send  any  message,  but  merely  wanted  to 
see  the  thing  work.  The  operator  remained  firm.  Then 
the  gentleman  got  angry.  He  informed  the  operator  that 
this  was  a  new  administration,  and  he  had  unlimited 
influence,  and  if  the  operator  did  not  at  once  exhibit 
the  machine,  he  would  have  him  removed.  The  operator 
simply  referred  his  visitor  to  the  Postmaster-General,  and 
the  interview  terminated. 

This  was  as  near  as  the  new  telegraph-office  got  to  col- 
lecting any  revenue  for  the  first  three  days.  On  April  4 
the  same  party  returned,  and  renewed  his  demand,  and 
finally  said  he  had  no  money  but  a  twenty-dollar  bill  and 
one  cent.  He  was  told  that  he  could  have  a  cent's  worth 
of  telegraphing,  if  that  would  answer,  to  which  he  agreed. 
Thereupon  Washington  sent  Baltimore  one  signal  which  by 
a  pre-arranged  code  meant,  "  What  time  is  it?  "  and  Bal- 
timore sent  back  a  single  signal  meaning  "One  o'clock." 
The  charge  for  the  two  characters  was  half  a  cent ;  but 
the  office-seeker  laid  down  the  whole  cent,  and  departed 
satisfied. 

This  was  the  entire  income  of  the  Washington  office  for 
the  first  four  days  of  April,  1845.  On  the  oth,  twelve  and 


THE  ELECTRIC   TELEGRAPH.  221 

a  half  cents  were  received.  The  6th  was  Sunday.  On 
the  7th,  the  receipts  ran  up  to  sixty  cents  ;  on  the  8th, 
to  $1.32  ;  on  the  9th,  to  $1.04.  It  is  worthy  of  remark, 
that  more  business  was  done  by  the  merchants  over  the 
line  after  the  tariff  was  laid,  than  when  the  service  was 
gratuitous. 

When  Morse  began  his  petitions  to  Congress,  several 
of  Henry's  friends,  knowing  what  he  had  accomplished, 
urged  that  he  present,  not  his  claims, — for  that  idea  he 
would  not  entertain,  —  but  evidence  of  the  fact  that  the 
principles  of  the  electro-magnetic  telegraph  belonged  to 
the  science  of  the  world.  Shortly  after  this,  Henry  made 
the  acquaintance  of  Morse,  whom  he  describes  as  an  "un- 
assuming and  prepossessing  gentleman,  with  very  little 
knowledge  of  the  general  principles  of  electricity,  magnet- 
ism, or  electro-magnetism."  Morse  made  no  claims  LO 
any  thing  but  "his  particular  machine  and  process  for  ap- 
plying known  principles  to  telegraphic  purposes  ;  "  and 
so,  adds  Henry,  "  instead  of  interfering  with  his  applica- 
tion to  Congress,  I  gave  him  a  certificate  in  the  form  of 
a  letter,  stating  my  confidence  in  the  practicability  of  the 
electro-magnetic  telegraph,  and  my  belief  that  the  form 
proposed  by  himself  was  the  best  that  had  been  pub- 
lished." 

Morse  obtained  his  first  patent  in  June,  1840.  Others 
were  subsequently  secured.  Infringements  of  all  sorts 
followed,  and  protracted  suits,  which  resulted,  however, 
in  Morse's  favor.  As  a  consequence,  Morse  is  popularly 
regarded  as  the  inventor  of  the  electro-magnetic  telegraph. 
He  has  no  right  to  the  title,  nor  did  he  himself  establish 
claim  thereto.  The  true  inventor  was  Joseph  Henry. 
Neither  is  Morse  entitled  to  the  credit  of  having  devised 
the  mechanism  of  the  telegraphic  instrument  attributed 
to  him ;  nor  of  the  dot-and-dash  alphabet  that  bears  his 


222  THE  AGE  OF  ELECTRICITY. 

name.  That  was  the  work  of  Alfred  Vail,  who  was  em- 
ployed by  Morse  to  improve  and  develop  the  invention. 
Vail  produced  the  first  so-called  Morse  instrument  in  the 
fall  of  1837,  entirely  of  his  own  design,  and  without  sug- 
gestion from  Morse,  and  arranged  it  to  emboss  alphabetic 
characters  devised  by  himself.  Morse,  in  such  late  rec- 
ognition as  he  made  of  what  Vail  had  done,  might  well 
have  heeded  the  lesson  in  magnanimity  given  by  Henry 
to  him. 

The  student  who  undertakes  to  glean  the  history  of  the 
telegraph  from  English  books  will  note  with  surprise  very 
little  mention  of  Henry.  In  fact,  most  English  writers 
claim  that  the  true  inventors  of  the  electro-magnetic  tele- 
graph were  Professors  Cooke  and  Wheatstone  of  England. 
This  leads  us  to  a  brief  review  of  what  was  going  on  in 
Europe  during  the  period  between  Henry's  first  dis- 
cover}7, and  the  successful  operation  of  Morse's  line  in 
this  country. 

In  1820  Ampere  merely  suggested  the  idea  that  a  series 
of  needles  could  be  deflected  by  currents  coming  over  as 
many  wires ;  eight  years  later,  Trebouillet  proposed  a 
single  wire  and  an  electroscope ;  and  finally  in  1832-33 
Schilling,  a  Russian  counsellor  of  state,  went  back  to  the 
multiple- wire  idea.  In  1833-35  two  German  scientists 
devised  a  needle  telegraph  in  which  a  galvanometer-needle 
was  made  to  move  by  currents  generated  by  a  coil  moved 
to  and  fro  on  a  magnet ;  the  transmitter  being,  in  fact,  a 
small  magneto-electric  machine. 

Meanwhile,  in  England,  Barlow's  conclusion  that  the 
electro-magnet  could  not  be  worked  over  long  distances 
of  wire  became  regarded  as  a  fixed  fact.  Cooke  in  1837, 
at  the  suggestion  of  Faraday,  applied  to  Professor  Wheat- 
stone  for  some  way  of  overcoming  his  "  inability  to  make 
the  electro-magnet  act  at  long  distances."  Wheatstone 


THE  ELECTRIC  TELEGRAPH.  223 

says  that  he  at  once  told  Mr.  Cooke  that  this  difficulty 
was  insurmountable,  and  exhibited  to  him  at  Kings  Col- 
lege experiments  which  supported  the  conclusion.  This 
was  not  only  after  Henry's  inventions  were  completed, 
but  even  after  Morse  had  made  his  applications  of  them. 
But  then,  what  could  so  distinguished  a  scientist  as 
Wheatstone  know  of  the  work  of  a  mere  professor  in  an 
American  college,  still  less  of  the  ideas  of  an  American 
portrait-painter?  Besides,  how  could  he  be  expected  to 
know  more  about  what  American  inventors  and  discoverers 
had  done,  than  the  Franklin  Institute,  which  held  its  meet- 
ings not  fifty  miles  from  Henry's  line,  and  which,  neverthe- 
less, solemnly  advised  the  Government  of  the  United  States 
to  experiment  upon  semaphores,  and  to  pay  $100,000  first 
cost,  and  $62,500  annual  charges,  for  a  series  of  them 
between  New  York  and  Washington  ? 

After  they  had  concluded  that  the  thing  could  not  be 
done,  Wheatstone  and  Cooke,  in  1837,  applied  for  an 
English  patent  for  it,  —  in  which,  among  other  devices, 
they  describe  five  wires  and  five  needles,  two  of  which 
indicated  the  letters  of  the  alphabet  placed  around,  — 
and  also  a  method  of  deflecting  telegraphic  magnetic 
needles  by  electro-magnets  ;  these  last  being  in  horseshoe 
form,  placed  opposite  one  another,  with  the  needle  between 
their  poles.  The  description  of  Wheatstone's  first  experi- 
ments, published  in  "Chambers'  Journal"  in  1870,  is 
worth  quoting:  "In  July,  1837,  wires  were  laid  down 
from  Eustou  Square  to  Camden  Town  Stations,  by  the 
sanction  of  the  North-western  Railway ;  and  Professor 
Wheatstone  sent  the  first  message  to  Mr.  Cooke  between 
the  two  stations.  The  professor  says,  ;  Never  did  I  feel 
such  tumultuous  sensation  before,  as  when,  all  alone  in 
the  still  room,  I  heard  the  nee'dles  click ;  and  as  I  spelled 
the  words,  I  felt  all  the  magnitude  of  the  invention  now 


224  THE  AGE  OF  ELECTRICITY. 

proved  to  be  practical  beyond  cavil  or  dispute.'  The 
form  of  telegraph  now  in  use  was  substituted  because  of 
the  economy  of  its  construction,  not  more  than  two  wires 
(sometimes  only  one)  being  required.  Of  course  several 
persons  claimed  to  have  invented  the  telegraph  before 
Professor  Wheatstone.  In  the  same  month  that  the  pro- 
fessor was  working  upon  the  North-western  Railway,  there 
was  one  in  operation  invented  by  Steinheil  of  Munich ; 
but  Wheatstone' s  patent  had  been  taken  out  in  the  month 
before.  An  American  named  Morse  claims  to  have  in- 
vented it  in  1832,  but  did  not  put  it  in  operation  till  1837. 
After  this  his  system  was  generally  adopted  in  the  United 
States.  It  is  a  recording  one." 

It  is  a  curious  fact  that  the  patent  granted  to  Wheat- 
stone  and  Cooke  in  this  country,  for  their  telegraph,  is 
earlier  in  date  by  just  ten  days  than  the  first  patent  ob- 
tained by  Morse. 

It  is  not  possible,  within  the  limits  of  the  present  work, 
to  trace  farther  the  history  of  the  telegraph.  Even  at 
the  early  period  of  which  we  have  been  writing,  it  had 
resolved  itself  into  two  great  types,  depending  upon  the 
kind  of  signals  given, — the  visual  or  needle  telegraph, 
the  electric  adaptation  of  the  old  semaphore  which  required 
the  receiver  to  watch  the  oscillations  of  a  needle  ;  and  the 
recording  telegraph,  wherein  the  current  was  made  to 
write  its  own  message  upon  a  slip  of  paper.  The  needle 
telegraph  is  not  in  use  in  the  United  States  :  it  is  essen- 
tially an  English  instrument,  and  is  still  largely  employed 
in  England  upon  the  railways.  Recording  instruments  of 
various  forms  are  used  in  the  United  States  ;  but,  in  the 
majority  of  instances  throughout  the  world,  telegraph- 
signals  are  read  by  the  clicking  sound  produced  by  the 
armature  of  the  receiving  magnet. 

The  amount  of  mechanical  ingenuity  expended  in  devis- 


THE  ELECTRIC  TELEGRAPH.  225 

ing  telegraphic  apparatus  has  been  and  still  is  wonderful. 
To  explain  even  the  best-known  systems  in  any  detail, 
would  require  the  dryest  of  descriptions  of  complicated 
mechanism,  extended  to  the  limits  of  a  cyclopaedia.  We 
shall  therefore  endeavor  to  indicate  what  the  telegraph 
can  do,  rather  than  how  its  machinery  operates  ;  resorting 
to  explanation  of  the  latter  only  where  it  may  be  indis- 
pensable to  an  understanding  of  the  results  achieved. 

If  we  stretch  a  wire  between  the  points  A  and  B,  and 
attach  the  ends  of  the  wire  to  plates  buried  in  the  earth, 
then  we  have  a  circuit.  If  we  place  a  battery  in  the  wire, 


as  in  Fig.  98,  then  a  current  will  pass  from  the  battery, 
to  and  along  the  wire,  in  the  direction  of  the  arrow  (for 
example) ,  and  thence  to  the  distant  earth  plate.  From 
this  earth  plate  the  current  will  apparently  return  by  way 
of  the  earth,  to  the  earth  plate  attached  to  the  battery, 
and  so  back  to  the  battery  itself. 

But  how  is  it  that  a  current  sent,  for  example,  over  a 
thousand  or  more  miles  of  wire,  can  find  its  way  back 
through  the  earth  to  its  source?  About  this  there  is  a 
great  deal  of  confusion.  One  writer  regards  the  earth  as 
a  reservoir  in  which  the  positive  electricity  on  the  one  side, 
and  the  negative  on  the  other,  are  absorbed  and  lost. 
Another,  considering  the  earth  still  as  a  reservoir,  con- 


226  THE  AGE   OF  ELECTRICITY. 

chides  that  it  offers  no  sensible  resistance  to  the  passage 
of  a  current.  A  third  holds  that  the  electricity  is  pumped 
into  the  earth  at  one  point,  and  out  of  it  at  another ;  and 
so  on  through  a  variety  of  hypotheses,  to  attempt  to 
reconcile  which  is  simply  bewildering. 

According  to  Faraday's  theory,  the  earth  plays  the  part 
of  a  conductor,  and  becomes  polarized  by  the  passage  of 
a  current,  the  same  way  as  any  other  part  of  the  circuit. 
Recent  experiments  of  Mr.  Willoughby  Smith  go  to  sub- 
stantiate this  view.  Mr.  Smith  says  that  "  the  current 
passes  through  the  earth  —  or  water,  which  amounts  to 
the  same  thing  —  as  through  an  ordinary  conductor,  in 
dispersed  and  curved  lines.  How  far  such  curves  extend, 
I  am  not  prepared  to  speak  positively  ;  "  but  they  prob- 
ably "  extend  over  the  whole  world,  and  what  are  termed 
the  magnetic  poles  of  the  same  are  the  immediate  cause 
of  the  lines  assuming  the  curved  form.  From  whatever 
source  a  current  emanates,  it  will  diffuse  itself  over  the 
whole  mass  of  matter  interposed,  without  in  any  way 
mixing  or  blending  with  a  current  or  currents  emanating 
from  any  other  source  or  sources.  The  nearest  analogy 
to  this  which  I  can  think  of  is  that  the  mind  of  each 
human  being  in  this  world  of  ours  is  constantly  directing 
what  are  called  lines  of  thought  from  its  brain,  or  battery, 
far  and  wide,  and  those  numberless  lines  of  thought,  so 
far  as  our  own  knowledge  extends,  never  blend  or  become 
confused,  but  go  and  return  each  one  to  the  source  from 
which  it  emanates  in  precisely  the  same  way  as  lines  of 
electro-motive  force  when  similarly  manipulated.  .  .  . 
Messages  by  electric  signals  have  been  sent  and  correctly 
received  through  a  submarine  cable  two  thousand  miles  in 
length,  the  earth  being  one-half  of  the  circuit,  by  the  aid 
of  electricity  generated  by  means  of  an  ordinary  gun-cap 
containing  one  drop  of  water ;  and,  small  though  the 


THE  ELECTRIC  TELEGRAPH.  227 

current  emanating  from  such  a  source  naturally  was,  yet 
I  believe  it  not  only  polarized  the  molecules  of  the  copper 
conductor,  but  also  in  the  same  manner  affected  the  whole 
earth  through  which  it  dispersed  on  its  way  from  the  out- 
side of  the  gun-cap  to  its  return  to  the  water  it  contained." 
The  battery  in  Fig.  98,  the  wire,  and  the  earth  are  in 
closed  circuit ;  that  is,  there  exists  a  path  through  which 
the  current  can  continuously  flow  until  the  battery  is 
exhausted.  If,  however,  we  should  break  the  wire,  and 
leave  the  ends  separated,  then  we  should  have  an  open 
circuit  over  which  no  current  passes  or  can.  pass  until  we 
unite  the  separated  ends  once  more.  If  we  attach  a  lever, 
—  or,  as  it  is  called,  a  key,  —  movable  by  the  hand,  to 


Wii-e 


Fig.  99. 

one  part  of  the  separated  wire,  as  in  Fig.  99,  and  ar- 
range the  key  so  that  at  will  we  can  cause  it  to  make 
contact  with  the  other  part  of  the  wire,  then,  if  we  leave 
the  key  open,  we  have  an  open  circuit ;  if  we  bring  the 
key  into  contact  with  the  opposite  part  of  the  wire,  so  that 
it  bridges  the  interval  between  the  two  separated  parts, 
then  the  effect  is  the  same  as  if  the  wire  were  continuous, 
and  we  have  a  closed  circuit. 

We  can  therefore  start  with  either  an  open  circuit  or  a 
closed  circuit.  If  we  choose  an  open  circuit,  every  time 
we  move  the  key  into  contact  with  the  opposite  part  of  the 
wire,  we  let  the  current  pass :  if  we  prefer  a  closed  circuit 
through  which  the  current  constantly  travels,  we  can  inter- 
rupt the  current  as  often  as  we  desire,  simply  by  moving 


228  THE  AGE  OF  ELECTRICITY. 

the  key  out  of  contact.  And  by  making  the  periods  of 
contact  or  the  periods  of  interruption  short  or  long,  or 
more  or  less  frequent,  we  can  allow  currents  varying  in 
duration  and  frequency  to  pass  over  the  line. 

At  the  opposite  extremity  of  the  line  to  that  at  which 
our  key  is  placed,  something  is  necessary  to  reveal  the 
currents  which  come  over ;  and  for  this  purpose,  as  we 
have  already  explained,  the  electro-magnet  is  employed. 

In  Fig.  100,  there  is  shown  a  closed  circuit.  Whenever 
we  press  down  the  key,  the  current  which  excites  the 
magnet  at  the  far  end  of  the  line  is  interrupted  ;  and 
the  magnet,  which  has  attracted  its  armature  to  its  pole,  re- 
leases it.  The  armature  is  thus  moved  from  one  position 


Fig.  100. 


to  another,  and  so  held  as  long  as  the  current  remains 
broken,  which  is  until  we  move  the  key  into  contact  and 
back  to  its  original  position.  Then  the  magnet  attracts 
its  armature  back  to  its  original  place. 

The  consequence  is,  therefore,  that  the  armature  at  the 
distant  end  of  the  line  copies,  so  to  speak,  the  movement 
of  the  key  at  the  sending  end.  If  the  key  is  held  down, 
and  the  circuit  opened,  for  a  certain  period,  the  armature 
remains  released  and  retracted  for  that  period :  if  the  key 
be  held  down  only  for  an  instant,  the  armature  is  instantly 
retracted  and  attracted.  Consequently,  in  order  to  send 
signals,  we  have  simply  to  manipulate  the  key  very  much 
as  a  key  of  a  piano  is  touched  when  it  is  desired  to  pro- 
duce a  note  of  greater  or  less  duration. 


THE  ELECTRIC  TELEGRAPH.  229 

It  will  be  remembered,  that,  in  describing  Morse's 
original  apparatus,  we  stated  that  a  pencil-point  rested 
upon  a  slip  of  moving  paper,  and  by  the  attraction  of  a 
magnet  made  sidewise  zigzag  marks  thereon.  Leaving 
out  the  idea  of  sidewise  motion,  suppose  we  move  the 
point  at  intervals  away  from  the  paper,  which  keeps  on 
travelling.  Then  we  shall  make  broken  lines,  long  or 
short,  depending  upon  the  length  of  the  intervals  of  time 
during  which  we  keep  the  pencil  away  from  the  paper. 
For  example :  suppose  above  a  magnet,  as  shown  in  Fig. 
101,  we  arrange  an  armature  fastened  to  one  end  of  a 
pivoted  lever  which  carries  a  pencil  at  its  opposite  end. 


Fig.  707. 


This  pencil  bears  against  the  under  side  of  a  strip  of 
paper,  which  is  moved  under  a  roller,  by  clock-work  or 
any  other  suitable  means.  So  long  as  the  current  comes 
over  the  line,  the  magnet  will  attract  its  armature,  and 
keep  the  pencil-point  pressed  against  the  paper,  on  which 
a  continuous  line  will  be  made.  But  if  the  current  is 
broken,  —  which  is  done  by  manipulating  the  key  at  the 
sending  end  of  the  line,  as  already  explained,  —  then  the 
magnet  will  no  longer  attract  its  armature,  and  the  pencil- 
point  end  of  the  lever  will  drop  down,  or  be  drawn  down 
by  a  spring,  so  that  the  pencil  will  no  longer  mark.  Now, 
we  have  only  to  agree  upon  an  alphabet  made  up  of  short 
lines  and  long  ones,  arranged  in  a  different  way  for  each 
letter,  to  make  the  apparatus  spell  out  words. 


230 


THE  AGE   OF  ELECTRICITY. 


The  shortest  signal  that  can  be  made  is,  of  course,  a 
dot ;  and  this  at  the  sending  end  involves  opening  the  cir- 
cuit and  closing  it  very  quickly  by  a  sudden  movement  of 
the  key.  The  dot  is  usually  taken  as  the  standard ;  and 
with  dots  are  combined  dashes,  which  may  be  regarded  as 
lines  produced  while  the  current  is  passing  three  times 
as  long  as  is  necessary  to  make  a  dot.  The  letter  A  may 
therefore  be  represented  by  a  dot  and  a  dash ;  £J,  by  a 
single  dot ;  F,  by  dot,  dash,  dot ;  and  so  on,  through 
various  combinations  in  which  the  spaces  or  intervals  be- 
tween the  dots  and  dashes  also  are  used  to  cause  varia- 
tions to  produce  a  different  symbol  for  each  letter  :  so  that 

any    one    knowing    these 


-drrtialttre  Jetxtr 


Fig.  102. 


symbols  can  read  the 
message  from  the  marked 
paper  as  easily  as  from  a 
printed  page. 

This  is  Morse's  record- 
ing system,  which  he  used 
on  his  first  line,  and  for 

which  Vail  invented  the  alphabet  of  dots  and  dashes  still 
employed  all  over  the  country. 

Nowadays,  however,  telegraph-operators  receive  mes- 
sages by  sound  ;  and  the  recording  part  of  Morse's  con- 
trivance is  little  used.  To  this  end  the  receiving  magnet 
is  arranged  about  as  indicated  in  Fig.  102.  Here  the  op- 
posite end  of  the  armature  moves  between  fixed  stops,  and 
strikes  them  alternately,  producing  a  sharp  click.  It  is  a 
great  puzzle  to  many  people,  to  understand  how  it  is  that 
a  telegraph-operator  sitting  beside  one  of  these  little  in- 
struments, which  appears  to  be  rattling  away  with  great 
rapidity,  manages  to  comprehend  what  it  says,  apparently 
as  well  as  if  the  instrument  actually  spoke  to  him.  Of 
course  long  practice  has  as  much  to  do  with  this  skill,  as 


THE  ELECTRIC  TELEGRAPH.  231 

it  has  in  enabling  any  one  to  comprehend  readily  a  foreign 
language.  The  lever,  however,  in  striking  its  stops,  pro- 
duces two  distinct  sounds,  according  as  it  meets  one  or  the 
other  stop.  When  a  dot  is  made,  the  lever  strikes  one 
stop,  and  instantly  afterward  the  other :  when  a  dash  is 
signalled,  there  is  a  longer  delay  between  the  sounds. 
The  two  sounds  are  in  themselves  just  alike  ;  but  the  dot 
and  dash,  to  a  practised  ear,  are  easily  distinguishable, 
because  there  is  a  longer  wait,  or  delay,  between  the  clicks 
which  begin  and  end  a  dash,  than  those  which  begin  and 
end  a  dot.  We  say,  to  a  practised  ear,  because  to  the 
ordinary  organ  there  is  no  apparent  difference.  The 
average  hearer  can  of  course  perceive  that  there  is  an 
irregularity  about  the  clicks,  and  that  they  do  not  come 
at  regular  intervals  like  the  beats  of  a  clock-pendulum  ; 
but  all  the  instruction  ever  given  by  written  description 
never  made  a  skilful  telegraphic  sound-reader,  and  proba- 
bly never  will.  To  learn  to  manipulate  a  key  so  as  to  send 
dots  and  dashes  with  fair  speed,  is  not  difficult ;  but  to 
translate  a  bewildering  succession  of  clicks,  spelling  out 
words  at  the  rate  of  perhaps  thirty  a  minute,  simultane- 
ously to  write  down  the  received  message,  and  to  do  this 
with  perhaps  other  instruments  in  the  room  clicking  away 
at  the  same  time,  and  perhaps  unlimited  conversation 
going  on,  and  all  this  with  the  knowledge  that  a  blunder 
may  involve  the  company  in  an  expensive  lawsuit,  is  not 
an  accomplishment  easily  acquired.  Yet  a  skilful  opera- 
tor can  send  and  receive  forty-five  words  per  minute. 

When  a  telegraph-line  is  of  considerable  length,  or  for 
any  other  reason  offers  much  resistance  to  the  passage  of 
the  current,  Henry's  invention  of  the  relay  is  employed  ; 
which  is  placed  in  the  main  line,  and  merely  performs  the 
duty  of  opening  and  closing  the  circuit  of  a  local  battery 
at  the  receiving  station,  which  in  turn  operates  the  sounder 


232 


THE  AGE   OF  ELECTRICITY. 


Fig.  103. 


already  described.  The  diagram  (Fig.  103)  will  render 
the  relay  arrangement  easily  understood.  The  current 
coming  over  the  line  excites  the  magnet  marked  "relay," 
which  attracts  its  armature,  and  thus  moves  the  latter  into 

contact  with  a  stop.  The 
circuit  of  the  local  battery  is 
thus  established  through  the 
magnet  of  the  sounder. 

The  closed-circuit  system 
which  is  in  almost  universal 
use  throughout  the  United 
States  is  shown  in  its  sim- 
plest form  in  Fig.  104.  At 
each  key  there  is  a  circuit-closing  lever  whereby  the  line 
is  kept  closed,  so  that  a  current  constantly  traverses  the 
line.  This  current  goes  from  the  main  battery  at  New 
York,  for  example,  through  the  circuit-closing  lever,  to 
the  relay  magnet 
which  attracts  its 
armature.  In  Fig. 
104  the  sounders 
and  local  batteries 
are  not  shown. 
But  when  this 
armature  is  at- 
tracted, it  makes 
contact  with  a 
stop,  and  thus 
completes  the  circuit  from  the  local  battery  through  the 
sounder  at  New  York.  Hence,  at  the  New- York  end, 
both  armatures  stand  normally  attracted.  After  passing 
through  the  New-York  relay,  the  current  goes  over  the 
ninety  miles  or  so  of  line  to  the  Philadelphia  relay,  which 
attracts  its  armature,  and  establishes  a  local  circuit  through 


Fig.  104. 


THE  ELECTRIC   TELEGRAPH.  233 

the  sounder  in  Philadelphia.  This  is  the  normal  condition 
of  affairs. 

Suppose  now  New  York  wants  to  send  a  despatch  to 
Philadelphia.  The  first  thing  that  the  New- York  operator 
does  is  to  open  his  circuit-closing  lever,  when  all  of  the 
armatures  both  at  his  and  at  the  Philadelphia  end  will 
be  released.  Then  he  manipulates  his  key,  making  and 
breaking  the  current  to  form  the  desired  signals  ;  and  as 
he  does  so,  all  of  the  armatures  at  both  ends  of  the  line 
will  respond,  so  that  the  Philadelphia  receiver  has  merely 
to  listen  to  the  clicks  of  his  sounder  to  receive  the  mes- 
sage. Meanwhile  the  New- York  sender's  instruments  keep 
clicking  too,  which  indicates  to  him  that  the  message  is 
reaching  Philadelphia.  If,  however,  his  instruments  should 
stop,  he  would  know  that  the  Philadelphia  man  had  opened 
the  circuit.  Then  he  would  close  his  own  lever,  and  wait 
for  a  message  from  Philadelphia  explaining  the  reason  of 
the  break, — such,  for  instance,  as  "  message  not  under- 
stood," or  something  of  that  sort.  The  instruments  at 
the  Philadelphia  end  being  the  same  as  those  at  the  New- 
York  end,  a  message  from  Philadelphia  to  New  York 
would  of  course  be  transmitted  in  the  same  way.  It  will 
be  seen,  however,  that  there  is  but  one  main-line  battery, 
which  is  at  the  New- York  end.  In  practice  this  battery  is 
usually  divided,  half  of  it  being  placed  at  each  terminal 
station.  As  many  as  forty  intermediate  stations  are  some- 
times operated  in  this  manner. 

So  far  we  have  described  simply  a  main  line,  the  cur- 
rent of  which  establishes  a  new  circuit  at  the  receiving 
end,  so  that  the  work  of  recording  the  message,  or  of 
operating  the  sounder,  is  thrown  upon  a  battery  at  that 
end.  But  suppose  we  have  to  telegraph  over  very  long- 
distances —  say  from  Augusta,  Me.,  to  San  Francisco, 
Cal.  A  single  main-line  battery  might  be  wholly  unable 


234  THE  AGE   OF  ELECTRICITY. 

to  send  its  current  through  so  much  resistance  ;  and  if  we 
divided  the  line  into  short  sections,  it  would  be  necessary 
for  the  operator  at  each  station  to  receive  and  understand 
the  message,  and  then  repeat  it  to  the  next  station.  In 
the  early  days  of  telegraphing,  this  was  in  fact  done  ;  but 
now  it  is  automatically  accomplished  by  a  simple  exten- 
sion of  the  relay  principle  known  as  "repeating."  In- 
stead of  there  being  simply  a  short  local  circuit  in  the 
receiving  station,  which  is  controlled  by  the  arriving  cur- 
rent, the  latter  governs  a  circuit  which  extends,  perhaps, 
a  long  distance  to  another  station.  The  current  which 
comes  to  station  No.  2  closes  contact  in  a  circuit  which 
extends  still  farther  to  station  No.  3,  and  so  on  from 
station  to  station,  until  the  sounder  at  the  far-distant  end 
of  the  series  of  lines  is  operated ;  just  as  if  one  could  fire 
a  gun,  and  with  the  bullet  strike  the  trigger  of  a  distant 
gun,  the  missile  from  which  would  fire  a  third  gun,  and  so 
on.  So  that,  in  practice,  suppose  a  message  to  be  sent  from 
Augusta,  at  which  place  the  battery  is  located.  When  the 
key  is  closed,  a  current  goes  over  the  line,  and  energizes 
a  magnet  at  New  York,  for  example.  This  magnet  then 
closes  the  circuit,  say,  between  New  York  and  Chicago, 
and  in  this  circuit  there  is  a  new  battery  located  at  New 
York.  The  current  from  New  York  closes  at  Chicago 
the  circuit  between  that  city  and  San  Francisco,  and  finally 
San  Francisco  receives  the  message  on  its  sounder  in  the 
usual  way.  Repeaters  are  also  often  used  for  connecting 
one  or  more  branch  lines  with  a  main  line,  for  the  purpose 
of  transmitting  press  news,  etc.,  simultaneously  to  differ- 
ent places.  This  enables  all  the  stations  in  connection 
to  communicate  with  each  other  as  readily  as  if  they  were 
situated  upon  the  same  circuit. 

The  use  of  repeaters  has  aided  many  very  wonderful 
feats  of  rapid  long-distance  telegraphing.     The  news  of 


THE  ELECTRIC  TELEGRAPH.  235 

the  Hanlan-Trickett  rowing  match  in  England,  in  1881, 
travelled  to  Sydney,  Australia,  a  distance  of  twelve  thou- 
sand miles,  in  one  hour  and  twenty  minutes.  The  distance 
from  Singapore  to  Sydney,  5,070  miles,  was  traversed  in 
thirty-five  seconds.  There  were  fourteen  repetitions  of 
the  message  en  route.  But  perhaps  the  most  extraordi- 
nary direct  long-distance  telegraphing  is  that  now  possible 
between  London  and  Calcutta,  —  seven  thousand  miles, — 
of  which  a  writer  in  the  London  ' '  Telegraphist ' '  gives 
the  following  graphic  account :  — 

"  In  the  basement  of  an  unpretentious  building  in  Old 
Broad  Street,  we  were  shown  the  Morse  printer  in  connec- 
tion with  the  main  line  from  London  to  Teheran.  We 
were  informed  that  we  were  through  to  Emden  ;  and  with 
the  same  ease  with  which  one  '  wires  '  from  the  city  to  the 
West  End,  we  asked  a  few  questions  of  the  telegraphist  in 
the  German  town.  When  we  had  finished  with  Emden,  we 
spoke  with  the  same  facility  to  the  gentleman  on  duty  at 
Odessa.  This  did  not  satisfy  us,  and  in  a  few  seconds  we 
were  through  to  the  Persian  capital  (Teheran) .  There  were 
no  messages  about,  the  time  was  favorable,  and  the  em- 
ployees of  the  various  countries  seemed  anxious  to  give  us 
an  opportunity  of  testing  the  capacity  of  this  wonderful  line. 

"T  H  N  (Teheran)  said,  'Call  Kurrachee ; '  and  in 
less  time  than  it  takes  to  write  these  words,  we  gained  the 
attention  of  the  Indian  town.  The  signals  were  good, 
and  our  speed  must  have  equalled  fifteen  words  a  minute. 
The  operator  at  Kurrachee,  when  he  learnt  that  London 
was  speaking  to  him,  thought  it  would  be  a  good  opportu- 
nity to  put  us  through  to  Agra  ;  and  to  our  astonishment 
the  signals  did  not  fail,  and  we  chatted  pleasantly  for  a 
few  minutes  with  Mr.  Malcom  Khan,  the  clerk  on  duty. 
To  make  this  triumph  of  telegraphy  complete,  Agra 
switched  us  on  to  another  line,  and  we  soon  were  talking 


236  THE  AGE   OF  ELECTRICITY. 

to  a  native  telegraphist  at  the  Indian  Government  cable 
station,  Calcutta.  At  first  the  gentleman  '  at  the  other 
end  of  the  wire  '  could  not  believe  that  he  was  really  in 
direct  communication  with  the  English  capital,  and  he 
exclaimed  in  Morse  language,  '  Are  you  really  London  ?  ' 
Truly  this  was  a  great  achievement.  Metallic  communi- 
cation without  a  break  from  London,  to  the  telegraph- 
office  in  Calcutta !  Seven  thousand  miles  of  wire  !  The 
signals  were  excellent,  and  the  speed  attained  was  not  less 
than  twelve,  perhaps  fourteen,  words  per  minute." 

One  of  the  most  paradoxical  of  all  the  applications 
of  electricity  is  that  which  appears  to  solve  that  rather 
insoluble  problem  of  how  to  make  two  locomotives  pass 
each  other  while  moving  in  opposite  directions  on  a 
single  track.  This  is  the  so-called  duplex  system  of  teleg- 
raphy, whereby  two  messages  are  transmitted  over  one 
wire  simultaneously  and  in  opposite  directions. 

To  explain  the  duplex  without  resort  to  technicalities, 
is  exceedingly  difficult,  chiefly  because  it  is  scarcely  pos- 
sible to  suggest  an  analogy  which  meets  all  conditions. 
It  should  be  remembered,  that,  in  dealing  with  electricity, 
our  ideas  of  lapse  of  time  are  very  apt  to  lead  us  alto- 
gether astray ;  and  we  frequently  consider  occurrences  as 
simultaneous,  because  they  seem  so  to  be  to  our  senses, 
when  in  fact  they  are  necessarily  successive.  So,  in  the 
case  of  the  duplex,  for  all  practical  purposes  two  mes- 
sages do  travel  in  opposite  directions  on  one  and  the  same 
wire  ;  but  probably  the  signals  in  one  direction  alternate  in 
inconceivably  small  periods  of  time  with  those  coming 
from  the  opposite  direction.  To  obtain  any  clear  idea 
of  the  duplex,  therefore,  it  is  necessary  to  forget  the 
apparent  paradox,  and  simply  to  regard  the  apparatus  as 
affording  means  whereby  each  of  two  widely  separated 
operators  may  control  an  instrument  at  the  end  of  the  line 


THE  ELECTRIC   TELEGRAPH.  237 

distant  from  him.  On  such  a  line,  at  each  end  there  is, 
of  course,  a  sending  key  and  a  receiving  instrument. 
But  ordinarily,  when  two  receivers  are  thus  connected,  a 
current  sent  upon  the  line  affects  both  of  them.  Hence 
if  A  at  one  station,  while  telegraphing  to  B  at  the  other, 
keeps  his  receiver  clicking  under  his  own  signals,  B  at  the 
other  end,  in  sending  to  A,  cannot  exercise  the  necessary 
control  over  A's  receiver ;  and  in  the  same  way,  if  B's 
receiver  is  constantly  disturbed  by  B,  it  cannot  correctly 
be  governed  by  the  signals  sent  by  A.  Therefore  the 
main  principle  of  the  duplex  is  to  arrange  matters  so  that 
A's  signals  will  affect,  not  A's  receiver,  but  B's  receiver ; 
and  conversely,  so  that  A's  receiver  will  respond  only  to 
B's  signals,  and  B's  receiver  to  A's  signals. 

There  are  several  ways  of  doing  this  ;  but  for  these,  the 
reader  is  referred  to  the  technical  treatises. 

The  diplex  is  a  system  by  which  two  messages  can  be 
sent  at  once  in  the  same  direction  ;  and  is  called  "  diplex  " 
in  contradistinction  to  the  "duplex,"  where  two  messages 
are  sent  simultaneously  in  opposite  directions.  In  the 
diplex,  the  two  keys  are  of  course  at  the  sending  station, 
and  the  two  relays  are  at  the  receiving  station.  Ke}'  num- 
ber one  sends  a  weak  current,  while  key  number  two  sends 
a  stronger  current.  The  two  relays  are  so  arranged  that 
one  will  respond  to  the  strong  current,  and  the  other  to 
the  weak  ;  when  both  currents  are  sent  at  once,  both  re- 
lays respond.  It  is  this  system,  using  both  poles  of  the 
battery  in  connection  with  the  so-called  bridge  duplex, 
which  forms  the  so-called  quadruples  of  Edison.  A  de- 
scription of  the  quadruplex  would,  however,  be  altogether 
too  technical  for  these  pages. 

Multiple  telegraphic  systems  have  for  their  object  the 
transmission  of  a  large  number  of  messages  simultaneously 
over  the  same  wire.  The  harmonic  system  is  one  of  the 


238  THE  AGE   OF  ELECTRICITY. 

most  ingenious  of  these,  although  it  has  never  come  into 
extended  practical  use.  It  depends  upon  thep  rinciple  of 
acoustics,  that  two  tuning-forks  or  tuned  reeds  will  vibrate  in 
unison,  and  be  set  in  vibration  one  by  the  other ;  whereas, 
of  two  forks  not  in  unison,  the  reverse  is  true.  Suppose, 
for  example,  half  a  dozen  tuning-forks  A,  B,  (7,  />,  E,  F, 
be  arranged  conveniently  together,  and  suppose  three  per- 
sons should  strike  three  other  tuning-forks  respectively  in 
unison  with  A,  B,  and  C of  the  series.  Then  the  air-waves 
produced  by  the  three  forks  set  in  vibration  would  affect 
only  A,  B,  C ;  and  these  three  forks  would  respond,  the 
others  remaining  silent.  Now  suppose  the  three  persons 
mentioned  should  strike  their  forks  simultaneously,  and  in 
a  particular  way  ;  as,  for  instance,  say  that  each  person 
should  make  the  signals  of  a  different  telegraphic  mes- 
sage in  the  Morse  alphabet  by  taps  on  his  fork.  Clearly, 
the  result  of  all  these  taps  sounding  together  would  be  a 
confused  jumble  to  the  ear,  but  when  the  combined  sounds 
reached  the  three  tuning-forks  A,  B,  and  C,  they  would 
be  disentangled.  The  tuning-fork  A  would  be  entirely 
indifferent,  audibly,  to  the  vibrations  affecting  B  and  (7, 
and  would  not  reproduce  them,  but  would  pick  out  and 
respond  only  to  those  emanating  from  a  fork  in  unison 
with  it.  So  also  of  forks  B  and  (7;  and,  consequently, 
three  messages  made  simultaneously  might  thus  be  trans- 
mitted through  the  air,  and  analyzed  at  the  receiving 
forks.  In  multiple  harmonic  telegraphy,  these  vibrations 
are  transmitted  by  the  electric  current,  through  a  wire, 
instead  of  by  waves  of  condensation  and  rarefaction  in 
the  air.  If  two  tuned  reeds  be  sounded  together,  then 
the  electrical  impulses  from  each,  moving  at  different 
rates  at  the  same  moment,  will  traverse  the  wire  simulta- 
neously, and  these  will  be  disentangled  by  each  of  twc 
receiving  reeds  vibrating  responsively  under  the  impulse 


THE  ELECTRIC  TELEGRAPH.  239 

of  the  transmitting  reed  in  unison  with  it.  In  this  manner 
two  messages  are  sent  simultaneously  over  a  single  wire, 
and  received  by  sound  separately  from  different  reeds. 
And  the  same  principle  governs  the  sending  of  more  mes- 
sages by  the  aid  of  a  greater  number  of  reeds,  and  under- 
lies the  construction  of  the  harmonic  telegraphs  of  Gray 
and  others. 

One  of  the  most  recent  inventions  in  multiple  teleg- 
raphy is  that  of  Mr.  Delany.  A  great  many  varieties  of 
telegraph-apparatus  depend  upon  synchronism  between  the 
movements  of  certain  devices  in  the  transmitting  apparatus, 
and  certain  other  devices  in  the  receiving  apparatus.  Two 
tuning-forks  are  said  to  be  synchronous  when  they  make 
the  same  number  of  vibrations  in  the  same  time,  and  have 
motions  exactly  similar.  Mr.  Delany  has  succeeded  in 
keeping  two  bodies,  separated  by  hundreds  of  miles, 
in  synchronous  rotation  for  periods  of  upward  of  seventy 
hours,  without  variation  during  that  time  of  the  one-thou- 
sandth part  of  a  second.  This  is  equivalent  to  two 
entirely  independent  bodies,  separated  from  each  other  by 
hundreds  of  miles,  starting  together  and  passing  through 
a  distance  of  nearly  one  hundred  miles  without  varying 
the  one-hundredth  part  of  an  inch  in  that  entire  distance, 
or  the  one-thousandth  part  of  a  second  during  that  entire 
time.  The  practical  consequence  is  that  circuits  ranging 
in  number  from  six  to  seventy-two,  according  to  their 
capacity,  have  been  obtained  over  a  single  wire,  admitting 
of  the  possibility  of  the  transmission  of  from  six  to 
seventy-two  separate  messages  at  practically  the  same 
time,  either  all  in  one  direction  or  any  portion  of  the 
whole  number  in  opposite  directions.  Another  extraor- 
dinary performance  of  Mr.  Delany's  apparatus  was  the 
automatic  transmission  of  a  single  dot  back  and  forth 
over  the  same  wire  between  Boston  and  Providence,  at 


240  THE  AGE  OF  ELECTRICITY. 

practically  the  same  instant  of  time,  travelling  over  dif- 
ferent circuits  in  rotation  backward  and  forward  for  five 
minutes,  during  which  time  it  travelled  four  hundred  and 
fifty  thousand  miles.  Mr.  Delany's  system  is  based  on 
two  main  principles :  first,  that  of  synchronism,  or  the 
simultaneous  motion  of  similar  pieces  of  apparatus  at 
two  different  places  ;  and,  second,  that  of  distributing  to 
several  telegraphists  the  use  of  a  wire  for  very  short  equal 
intervals  of  time,  so  that,  practically,  each  operator  has 
the  line  to  himself  during  these  periods. 

Farther  on,  we  shall  see  the  great  importance  of  syn- 
chronism in  fac-simile  telegraphy.  But,  in  connection 
with  the  transmission  of  messages  in  the  usual  way,  Mr. 
Delany's  apparatus  greatly  increases  the  capacity  of  every 
wire,  and  probably  at  the  present  time  allows  of  more 
messages  being  simultaneously  transmitted  over  a  given 
conductor,  at  the  same  time,  than  any  other  telegraphic 
system. 

It  is  of  course  needless  here  to  go  into  the  minute 
details  and  very  complex  mechanism  employed  in  multiple 
telegraphy :  nor,  in  fact,  shall  we  attempt,  in  the  many 
forms  of  intricate  devices  which  must  find  mention  here, 
to  do  more  than  generally  outline  what  they  will  accom- 
plish. As  we  have  seen,  duplex,  quadruplex,  and  other 
multiple  telegraphic  systems  increase  the  capacity  of  wires, 
and  expedite  business  through  rendering  it  possible  to 
send  many  messages  at  one  time.  There  are  many  sys- 
tems, however,  which  provide  for  very  rapid  transmission. 

It  will  easily  be  understood,  that,  where  telegraphic 
transmission  depends  upon  the  manipulation  of  a  key  by 
the  human  hand,  a  limit  of  speed  is  very  soon  reached. 
And  not  only  this,  but  the  human  machine  tires  and  makes 
errors  ;  the  signals  lose  legibility  and  clearness  ;  and,  in 
short,  the  various  accidents  and  failures  incident  to  all 


THE  ELECTRIC  TELEGRAPH.  241 

handiwork  become  manifest  in  greater  or  less  degree. 
When,  however,  manipulation  by  the  operator  is  replaced 
by  the  action  of  a  machine,  then  not  only  great  speed  but 
precision  within  certain  limits  is  obtained  :  and  hence  auto- 
matic instruments,  both  for  the  sending  and  receiving  of 
telegraphic  messages,  have  been  invented  and  are  in  use. 

Automatic  telegraphy  is  largely  employed  in  England, 
where  it  was  first  proposed  in  1846  by  Alexander  Bain. 
He  punched  broad  dots  and  dashes  in  paper  ribbon,  which 
was  drawn  with  uniform  velocity  over  a  metal  roller  and 
beneath  brushes  of  wire,  which  thus  replaced  the  key  ;  for, 
whenever  a  hole  occurred,  a  current  was  sent  by  the 
brushes  coming  in  contact  with  the  roller.  The  same  idea 
is  now  applied  to  the  musical  instrument  known  as  the 
mechanical  orguinette,  in  which  a  strip  of  paper  having 
apertures  of  various  sizes  is  moved  in  front  of  the  melo- 
deon  reeds  so  as  to  control  the  air  supply  to  them,  and 
hence  the  notes  produced.  Bain  used  as  a  recording  in- 
strument his  chemical  marker,  wherein  the  current  was  re- 
ceived through  a  strip  of  paper  moistened  with  a  chemical 
solution  which  became  decomposed  on  the  passage  of  the 
current,  so  that  the  contact  point  in  touching  the  paper 
caused  dots  and  dashes  of  a  bright  blue  color  to  appear. 

The  apparatus  used  throughout  Great  Britain  is  that 
invented  by  Professor  Wheatstone.  Its  construction  is 
too  complicated  for  description  here ;  but,  in  general 
terms,  it  includes  a  punching-machine  for  producing  the 
perforated  strips  of  paper,  a  transmitting  apparatus 
through  which  these  strips  are  very  rapidly  passed,  and 
a  receiving  device  which  marks  on  another  strip  dots  and 
dashes  in  ink.  The  punching-machine  will  make  the  holes 
in  three  or  even  four  strips  at  a  time,  and  in  the  hands  of 
an  experienced  operator  will  punch  at  the  rate  of  forty 
words  a  minute.  The  disposition  of  holes  in  a  strip  when 


242  THE  AGE  OF  ELECTRICITY. 

thus  prepared  is  shown  in  Fig.  105  ;  the  large  openings 
being  for  the  message,  and  the  centre  row  of  small  ones 
serving  to  receive  the  teeth  of  a  wheel  which  in  turning 
moves  the  strip  along  at  uniform  speed.  When  the  paper 
is  thus  prepared  it  is  run  through  the  transmitter,  which  is 
permitted  to  operate  to  send  a  current  whenever  certain 
moving  rods  can  pass  through  the  holes  and  establish  a 
contact,  the  currents  being  alternately  positive  and  nega- 
tive. If  a  succession  of  currents  in  reverse  directions  are 
caused  to  pass  upon  the  line,  the  receiver  at  the  opposite 
end  will  record  a  series  of  dots.  To  make  a  dash,  one 
reversal  of  the  current  is  missed ;  and,  in  brief,  the  func- 


Fig.  1C5. 

tion  of  the  paper  is  so  to  regulate  the  motion  of  the  trans- 
mitter as  to  produce  reversal,  or  missing  of  reversal,  of 
the  current  at  the  proper  moments,  and  thus  to  cause  the 
current  to  flow  in  such  a  way  as  to  form  dots  and  dashes. 
The  speed  is  determined  by  the  rate  at  which  the  receiver 
can  receive  ;  because  the  apparatus  contains  a  controlling 
electro-magnet  which  takes  time  to  be  magnetized  and 
demagnetized,  and  hence,  if  the  current  reverses  too 
quickly,  the  marks  will  run  together  instead  of  being 
separate,  and  distinct.  The  maximum  useful  speed  is 
about  a  hundred  and  thirty  words  per  minute  on  a  short 
line.  One  strip  of  punched  ribbon  will  do  for  any  number 
of  circuits,  so  that  from  a  central  telegraph-station  a 
single  strip  disseminates  news  to  many  places. 


THE  ELECTRIC  TELEGRAPH.  243 

With  Edison's  system  of  automatic  transmission,  a 
much  greater  speed  than  this  has  been  obtained.  The 
receiving  apparatus  here  consists  simply  of  a  wire  tipped 
with  tellurium,  which  always  rests  on  the  moistened  paper. 
The  effect  of  the  current  is  to  decompose  the  water  in  the 
paper,  and  through  the  effect  of  the  tellurium  the  contact 
point  makes  a  dark  mark.  Mr.  Edison  in  this  way  claims 
to  have  transmitted  3,150  words  in  a  minute,  on  a  line 
between  New  York  and  Washington. 

We  have  now  seen  what  can  be  done  in  the  way  of  quick 
transmission.  Next  in  importance  is  legibility  at  the  re- 
ceiving end  ;  or,  rather,  the  possibility  of  receiving  mes- 
sages, not  in  dots  and  dashes,  but  in  ordinary  characters. 
For  this  purpose  type-printing  and  autograph  systems  are 
employed.  The  first  printing  telegraph  actually  used  was 
that  devised  by  Royal  E.  House  of  Vermont  in  1846,  — 
now  obsolete.  It  was  followed  by  Hughes's  system,  in 
which  the  principle  of  synchronism  between  the  sending 
and  receiving  instruments  entered  materially  into  the  suc- 
cess of  its  working.  Hughes's  apparatus  is  not  used  in 
this  country.  It  has  two  type-wheels  kept  rotating  syn- 
chronously together  at  each  station  by  means  of  a  train 
of  gearing  provided  with  a  governor.  Connected  to  the 
mechanism  is  a  transmitting  cylinder,  arranged  with  and 
controlled  by  a  keyboard  having  a  key  for  each  letter  of 
the  alphabet.  A  printing-lever,  controlled  by  an  electro- 
magnet placed  in  the  main  line,  causes  the  printing  of  a 
letter  upon  a  long  fillet  of  paper  while  the  type-wheel  is 
rapidly  moving.  This  movement  is  caused  by  the  energiz- 
ing of  the  controlling  magnet  by  the  transmission  of  a 
single  wave  of  electricity  from  the  distant  station  at  the 
proper  time.  Simultaneously  with  the  printing  of  a  letter, 
the  type-wheel,  by  the  action  of  the  printing-lever,  is 
thrown  slightly  forward  or  backward,  thus  correcting  at 


244  THE  AGE  OF  ELECTEICITY. 

every  impression  any  slight  variation  in  the  synchronous 
movement  of  the  wheel. 

The  printed  despatches  on  the  long  slips  of  paper  now 
delivered  by  the  Western  Union  Telegraph  Company  are 
transmitted  by  Mr.  G.  M.  Phelps's  electro-motor  telegraph. 
In  this  system,  the  gearing  of  the  Hughes  apparatus  is 
replaced  by  a  simple  but  powerful  electro-motor.  As  in 
the  Hughes  machinery,  the  transmitting  device  and  type- 
wheel  of  the  receiving  instrument  are  caused  to  revolve 
synchronously  under  control  of  a  governor,  and  each  sepa- 
rate letter  is  printed  by  a  single  pulsation  of  the  electric 
current,  of  a  determinate  and  uniform  length,  transmitted 
at  a  determinate  time  ;  but,  unlike  the  Hughes  apparatus, 
the  motion  of  the  type-wheel  is  arrested  while  each  letter 
is  being  printed,  and  it  is  automatically  released  the  in- 
stant the  impression  has  been  effected.  By  this  means  a 
very  high  speed  of  transmission  has  been  attained. 

There  is  one  form  of  printing  telegraph  which  is  notable 
for  the  danger  attending  its  use.  It  has  probably,  inno- 
cently, been  the  means  of  more  injury  to  the  human  race 
than  the  most  potent  of  electrical  torpedoes,  which  it  re- 
sembles occasionally  in  effect,  —  that  is,  metaphorically 
speaking.  We  allude  to  the  stock  exchange  "ticker" 
when  combined  with  a  widely  fluctuating  market.  For 
the  benefit  of  those  who  have  never  watched  the  motions 
of  the  intricate  little  mechanism, — let  us  say,  while  wait- 
ing for  the  next  quotation,  —  it  may  be  explained,  that 
there  is  usually  a  t}Tpe-wheel  rotated  by  a  lever  from  an 
electro-magnet.  The  magnet  is  excited,  and  the  lever 
worked,  by  pulsations  over  the  wire.  The  lever  turns  the 
type-wheel  step  by  step.  Usually  there  are  two  type- 
wheels  ;  one  printing  the  cabalistic  letters  which  indicate 
the  name  of  the  stock,  and  the  other  the  quotation  in 
numbers.  When  a  letter  or  number  is  to  be  printed,  the 


THE  ELECTRIC  TELEGRAPH.  245 

proper  wheel  is  brought  into  position,  and  then  another 
magnet  operates  to  bring  the  "tape"  into  contact  with 
the  type. 

Despatches  may  be  sent  automatically,  and  received  in 
printed  characters,  by  several  systems,  of  which  Bonnelli's 
is  an  example.  The  message  is  set  up  in  ordinary  type, 
which  are  connected  to  the  battery  and  earth.  Over  the 
face  of  the  type  passes  a  comb  of  fine  points  of  wire, 
each  point  being  connected  to  a  separate  line  proceeding 
to  the  distant  station,  and  the  line  wires  there  being  con- 
nected to  another  and  similar  comb,  which  is  moved  over 
chemically  prepared  paper.  When  the  comb  at  the  send- 
ing end  is  rubbed  over  the  raised  parts  of  the  characters, 
the  comb  at  the  receiving  end  receives  a  current  which 
decomposes  the  chemicals  in  the  paper,  producing  a  mark 
similar  to  the  character  traversed.  Little  use  has  been 
made  of  systems  of  this  character. 

The  autographic  telegraph  is  one  of  the  most  ingenious 
of  the  various  known  systems.  It  is  not  used  in  this 
country,  although  recently  the  improvements  in  effecting 
synchronism  have  directed  anew  the  attention  of  inventors 
to  its  possibilities.  It  transmits  the  handwriting  of  the 
sender,  and  also  simple  drawings.  Its  advantages  at  pres- 
ent appear  to  depend  on  whatever  benefits  may  be  derived 
from  these  capabilities  ;  thus  it  may  be  useful  to  send 
sketches  and  illustrations  to  newspapers,  or  to  verify  sig- 
natures, or  to  telegraph  bank-checks  in  facsimile :  but 
beyond  this,  it  has  not  much  promise.  Its  operation  de- 
pends upon  synchronism  at  both  ends  of  the  line.  Cas- 
selli's  apparatus,  which  is  used  in  France,  consists  of  two 
large  pendulums  kept  swinging  in  unison  by  electro-mag- 
nets placed  in  the  line  wire.  One  pendulum  transmits 
electric  waves  at  certain  intervals,  which,  acting  upon  the 
magnets,  cause  them  to  correct  variations  from  exact 


246  THE  AGE  OF  ELECTRICITY. 

unison  of  swing.  The  message  for  transmission  is  written 
upon  metallic  foil,  with  a  non-conducting  ink  :  this  is  laid 
upon  a  platen  connected  to  the  earth  through  a  battery. 
A  fine  platinum  wire  connected  to  the  line  wire  is  recipro- 
cated from  one  end  of  the  foil  to  the  other ;  the  foil  being 
advanced  one-hundredth  of  an  inch  after  each  reciproca- 
tion, until  the  point  has  passed  over  the  whole  of  the  foil. 
The  platinum  point,  when  passing  over  the  foil,  allows 
the  current  from  the  battery  to  go  to  the  line.  At  all 
points,  however,  where  it  passes  over  the  non-conducting 
ink  with  which  the  message  is  written,  the  current  is  pre- 
vented from  passing  to  line.  At  the  distant  station  a 
similar  point  is  reciprocated  over  a  platen  upon  which  is 
laid  a  sheet  of  chemically  prepared  paper:  the  passage 
of  the  circuit  through  the  reciprocated  point  and  moistened 
paper  causes  a  blue  mark  to  appear.  If  both  pendulums 
are  started  at  the  same  instant,  the  form  of  the  metallic 
foil  upon  which  the  message  is  written  will  be  reproduced 
upon  the  chemical  paper  by  blue  lines  blending  one  into 
the  other.  But  owing  to  the  non-transmission  of  any  cur- 
rent where  the  transmitting  point  passes  over  the  non- 
conducting ink,  no  mark  will  appear ;  hence  the  message 
would  be  inscribed  in  white  characters  on  a  blue  ground, 
were  it  not  for  an  ingenious  little  device  which  reverses 
the  action,  causing  the  characters  to  appear  in  blue.  In 
Fig.  106  is  represented  a  design  as  prepared  and  then  trans- 
mitted in  facsimile  by  Casselli's  apparatus.  In  the  more 
recent  forms  of  writing  telegraph,  notably  Cowper's,  a 
different  principle  is  employed  ;  the  message,  in  fact,  being 
transmitted  by  the  act  of  writing  it.  The  idea  followed  is, 
that  every  position  of  the  point  of  a  pen,  as  it  forms  a 
letter,  can  be  determined  by  its  distance  from  two  fixed 
lines  —  say,  the  adjacent  edges  of  the  paper.  Hence  if 
these  distances,  so  to  speak,  are  transmitted  by  telegraph, 


THE  ELECTRIC  TELEGRAPH. 


247 


and  recombined,  so  as  to  give  a  resultant  motion  to  a  dupli- 
cate pen,  a  duplicate  copy  of  the  original  writing  is  pro- 
duced. Cowper  uses  two  separate  circuits,  one  to  transmit 
the  vertical,  the  other  the  horizontal,  movements  of  his  pen. 

And  now  we  come  to  the  most  wonderful  of  all  tele- 
graphs, — -  that  which  transmits  messages  from  continent 
to  continent,  for  thousands  of  miles,  under  the  depths  of 
the  sea.  "Does  it  not  seem  all  but  incredible  to  you,'* 
said  Edward  Everett  in  his  oration  at  the  opening  of 


Original. 


Fig.  106. 


Facsimile. 


Dudley  Observatory,  "  that  intelligence  should  travel  for 
two  thousand  miles  along  those  slender  copper  wires  far 
down  in  the  all- but  fathomless  Atlantic,  never  before  pen- 
etrated by  aught  pertaining  to  humanity,  save  when  some 
foundering  vessel  has  plunged  with  her  hapless  company 
to  the  eternal  silence  and  darkness  of  the  abyss  ?  Does 
it  not  seem,  I  say,  all  but  a  miracle  of  art,  that  the 
thoughts  of  living  men  —  the  thoughts  that  we  think  up 
here  on  the  earth's  surface,  in  the  cheerful  light  of  day — 
about  the  markets  and  the  exchanges,  and  the  seasons, 
and  the  elections  and  the  treaties  and  the  wars,  and  all  the 
fond  nothings  of  daily  life,  should  clothe  themselves  with 


248  THE  AGE  OF  ELECTRICITY. 

elemental  sparks,  and  shoot  with  fiery  speed  in  a  moment, 
in  the  twinkling  of  an  eye,  from  hemisphere  to  hemi- 
sphere, far  down  among  the  uncouth  monsters  that 
wallow  in  the  nether  seas,  along  the  wreck-paved  floor, 
through  the  oozy  dungeons  of  the  ray  less  deep ;  that  the 
last  intelligence  of  the  crops,  whose  dancing  tassels  will 
in  a  few  months  be  coquetting  with  the  west  wind  on  these 
boundless  prairies,  should  go  flashing  along  the  slimy 
decks  of  old  sunken  galleons  which  have  been  rotting  for 
ages ;  that  messages  of  friendship  and  love,  from  warm 
living  bosoms,  should  burn  over  the  cold  green  bones  of 
men  and  women  whose  hearts,  once  as  warm  as  ours, 
burst  as  the  eternal  gulfs  closed  and  roared  over  them, 
centuries  ago !  " 

It  is  not  definitely  known  who  originated  the  idea  of 
submarine  telegraph-lines.  The  notion  was  often  dis- 
cussed long  before  it  even  approached  successful  realiza- 
tion. The  first  working-line  was  laid  down  by  Professor 
Morse,  between  the  Battery  in  New- York  City  and  Gov- 
ernor's Island.  This  was  in  October,  1842.  What  Morse 
might  have  demonstrated  with  that  line,  can  only  be  con- 
jectured. It  came  to  an  untimely  ending.  The  very  next 
morning  after  it  had  been  laid,  some  conscienceless  mari- 
ners hauled  up  the  wire  on  their  anchor,  and,  probably 
realizing  its  advantages  if  devoted  to  splicing  their  stand- 
ing rigging,  cut  off  and  confiscated  as  much  of  it  as  they 
conveniently  could.  In  the  same  year  Col.  Samuel  Colt, 
of  revolver  fame,  put  down  a  submarine  line  between  Fire 
Island  and  Coney  Island  and  New- York  City,  and,  it  is 
said,  successfully  operated  it.  In  Europe  the  first  sub- 
marine line  was  laid  by  Lieutenant  Siemens,  between 
Deutz  and  Cologne,  across  the  Rhine,  a  distance  of  about 
hslf  a  mile  ;  and  on  this  wire  gutta-percha  was  first  used 
as  an  insulating  covering.  The  first  sea-line  extended 


THE  ELECTRIC  TELEGRAPH.  249 

between  Dover  and  Calais,  a  distance  of  twenty-four  miles, 
and  was  laid  in  1850. 

The  earliest  suggestion  of  the  possibility  of  a  trans- 
atlantic cable  appears  to  have  been  made  by  Gen.  Horatio 
Hubbell  and  Mr.  J.  H.  Sherburne  of  Philadelphia,  who 
united  in  a  memorial  which  was  presented  to  the  United- 
States  Senate  by  Vice-President  Dallas,  and  to  the  House 
of  Representatives  by  Hon.  J.  R.  Ingersoll,  on  Jan.  29, 
1849.  In  this  memorial  the  existence  of  the  plateau  or 
table-land  between  Newfoundland  and  Ireland  is  first 
announced  to  the  world  as  the  course  over  which  the  tele- 
graph cable  might  be,  and  over  which  it  finally  was,  suc- 
cessfully laid.  The  Senate  was  inclined  to  ignore  the 
subject,  and  not  even  refer  it  to  the  limbo  of  a  committee. 
But  one  senator,  Mr.  Jefferson  Davis,  finally  moved  its 
reference  to  the  Committee  on  Commerce,  remarking  that 
"the  world  was  not  yet  prepared  for  the  project,  but 
might  be  soon."  Congress  did  not  grant  the  memorialists' 
request  for  a  vessel  to  make  the  necessary  soundings  ;  but 
five  years  later  Lieutenant  Berryman  conducted  the  sur- 
veys of  the  ocean  bottom  upon  which  Lieutenant  Maury 
made  the  reports  which  determined  the  cable  route  over 
the  plateau. 

The  first  attempt  to  lay  a  transatlantic  cable  was  made 
in  August,  1857.  After  about  380  miles  had  been  sub- 
merged, the  engineer  thought  that  there  was  not  sufficient 
strain  on  the  line,  and  ordered  more  applied.  It  was  not 
properly  done,  and  the  cable  snapped.  In  August,  1858, 
the  work  was  successfully  accomplished  ;  the  cable  extend- 
ing from  Valentia  Bay,  Ireland,  to  Trinity  Bay,  New- 
foundland, a  distance  of  1,950  miles.  Congratulatory 
messages  were  interchanged  between  the  Queen  and  the 
President,  and  a  few  other  despatches  were  sent  during 
the  ensuing  fortnight ;  and  then  the  cable  refused  to  work. 


250  THE  AGE  OF  ELECTRICITY. 

A  defect  in  it  was  found,  but  all  attempts  to  remedy  it 
proved  unsuccessful. 

Of  course,  a  good  many  people  had  important  despatches 
coming  over  the  cable,  or  expected  to  send  them  ;  and 
when  it  began  to  fail,  there  were  innumerable  messages 
sent  to  Trinity  Bay  to  find  out  what  the  trouble  was.  The 
manager  there,  an  electrician  named  De  Sauty,  usually 
sent  back  the  most  re-assuring  replies,  and  continued  quite 
roseate  in  his  anticipations  until  the  cable  positively  refused 
to  transmit  any  thing  more,  and  then  he  disappeared  from 
public  gaze.  All  this  has  been  told  in  verse  by  that  most 
charming  of  humorists,  Dr.  Oliver  Wendell  Holmes,  in 
the  following  poem,  which,  as  the  Professor  at  the  Break- 
fast Table,  he  declares  to  be  his  "  only  contribution  to 
the  great  department  of  ocean-cable  literature.  As  all 
the  poets  of  this  country  will  be  engaged  for  the  next  six 
weeks  in  writing  for  the  premium  offered  by  the  Crystal- 
Palace  Company  for  the  Burns  Centenary  (so  called,  ac- 
cording to  our  Benjamin  Franklin,  because  there  will  be 
na'ry  a  cent  for  any  of  us) ,  poetry  will  be  very  scarce  and 
dear.  Consumers  may  consequently  be  glad  to  take  the 
present  article,  which  by  the  aid  of  a  Latin  tutor  and  a 
professor  of  chemistry  will  be  found  intelligible  to  the 
educated  classes." 

DE  SAUTY.1 

AN  ELECTRO-CHEMICAL  ECLOGUE. 

PROFESSOR.  BLUE-NOSE. 

PROFESSOR. 

Tell  me,  O  Provincial !  speak,  Ceruleo-Nasal ! 
Lives  there  one  De  Sauty  extant  now  among  you, 
Whispering  Boanerges,  son  of  silent  thunder, 
Holding  talk  with  nations  ? 

1  Reprinted  by  kind  permission  of  Dr.  Holmes. 


THE  ELECTRIC  TELEGRAPH.  251 

Is  there  a  De  Sauty  ambulant  on  Tell  us 
Bifid-cleft  like  mortals,  dormient  in  night-cap, 
Having  sight,  smell,  hearing,  food-receiving  feature 
Three  times  daily  patent  ? 

Breathes  there  such  a  being,  O  Ceruleo-Nasal  ? 
Or  is  he  a  my  thus,  — ancient  word  for  "  humbug,"  — 
Such  as  Livy  told  about  the  wolf  that  wet-nursed 
Romulus  and  Remus  ? 

Was  he  born  of  woman,  this  alleged  De  Sauty, 
Or  a  living  product  of  galvanic  action 
Like  the  acarus  bred  in  Crosse's  flint  solution  ? 
Speak,  thou  Cyano-Rhinal! 


BLUE-NOSE. 

Many  things  thou  askest,  jackknife-bearing  stranger, 
Much-conjecturing  mortal,  pork-and-treacle  waster, 
Pretermit  thy  whittling,  wheel  thine  ear-flap  toward  me. 
Thou  shalt  hear  them  answered. 

When  the  charge  galvanic  tingled  through  the  cable 
At  the  polar  focus  of  the  wire  electric, 
Suddenly  appeared  a  white-faced  man  among  us: 
Called  himself  "Ds  SAUTY." 

As  the  small  opossum  held  in  pouch  maternal 
Grasps  the  nutrient  organ  whence  the  term  mammalia, 
So  the~unknown  stranger  held  the  wire  electric, 
Sucking  in  the  current. 

When  the  current    strengthened,  bloomed   the  pale-faced 

stranger,  — 

Took  no  drink  nor  victual,  yet  grew  fat  and  rosy, 
And  from  time  to  time  in  sharp  articulation 
Said,  "All  right!  DE  SAUTY." 

From  the  lonely  station  passed  the  utterance,  spreading 
Through  the  pines  and  hemlocks  to  the  groves  of  steeples, 
Till  the  land  was  filled  with  loud  reverberations 
Of  "All  right!  DE  SAUTY." 


252  THE  AGE  OF  ELECTRICITY. 

When  the  current  slackened,  drooped  the  mystic  stranger, 
Faded,  faded,  faded,  as  the  stream  grew  weaker, 
Wasted  to  a  shadow,  with  a  hartshorn  odor 
Of  disintegration. 

Drops  of  deliquescence  glistened  on  his  forehead, 
Whitened  round  his  feet  the  dust  of  efflorescence, 
Till  one  Monday  morning,  when  the  flow  suspended, 
There  was  no  De  Sauty; 

Nothing  but  a  cloud  of  elements  organic,  — 
C,  O,  H,  N,  Ferrum,  Chlor.,  Flu.,  Sil.,  Potassa, 
Calc.,Sod.,  Phosph.,  Mag.,  Sulphur,  Mang.  (?),  Alumin.  (?), 

Cuprum  ( ?), 
Such  as  man  is  made  of. 

Born  of  stream  galvanic,  with  it  he  had  perished. 
There  is  no  De  Sauty,  now  there  is  no  current ! 
Give  us  a  new  cable,  then  again  we'll  hear  him 
Cry  "All  right!  DE  SAUTY." 

Shortly  after  the  failure  of  the  first  Atlantic  cable, 
other  deep-sea  cables  became  inoperative,  and  immense 
sums  of  money  were  lost.  In  1865  the  immense  "  Great 
Eastern"  steamship,  which  had  proved  a  veritable  white 
elephant  to  its  owners,  was  fitted  for  service  to  transport 
a  new  cable.  After  about  half  of  this  line  had  been  laid, 
it  broke,  and  the  hapless  promoters  of  the  enterprise 
feared  that  some  three  million  dollars  had  been  added  to 
the  great  aggregate  of  losses  already  incurred.  Prepara- 
tions were,  however,  at  once  made  for  another  attempt 
during  the  following  year.  The  managers  of  the  enter- 
prise, at  the  head  of  which  was  Mr.  Cyrus  W.  Field,  had 
indomitable  faith  in  its  practicability.  A  close  watch 
was  kept  on  the  broken  line,  now  resting  on  the  ocean- 
bed.  u  Night  and  day,"  says  an  English  journal  of 
the  time,  "  for  a  whole  year  an  electrician  was  always 


THE  ELECTRIC  TELEGRAPH.  253 

on  duty,  watching  the  tiny  ray  of  light  through  which 
signals  are  given  ;  and  twice  every  day  the  whole  length 
Of  wire  —  1,240  miles  —  was  tested  for  conduction  and 
insulation.  The  object  of  observing  the  ray  of  light 
was  of  course  not  any  expectation  of  a  message,  but 
simply  to  keep  an  accurate  record  of  the  condition  of  the 
wire.  Sometimes,  indeed,  wild  incoherent  messages  from 
the  deep  did  come  ;  but  these  were  merely  the  results  of 
magnetic  storms  and  earth-currents,  which  deflected  the 
galvanometer  rapidly,  and  spelt  the  most  extraordinary 
words,  and  sometimes  even  sentences  of  nonsense,  upon 
the  graduated  scale  before  the  mirror.  Suddenly,  early 
one  morning  the  observer  noticed  a  peculiar  flicker  of  the 
light  which  to  his  experienced  eye  showed  that  a  message 
was  on  hand.  In  a  few  minutes  afterward,  the  unsteady 
flickering  was  changed  to  coherency,  and  at  once  the  cable 
began  to  speak,  to  transmit  the  appointed  signals  which 
indicated  human  purpose  and  method  at  the  other  end, 
instead  of  the  hurried  signs,  broken  speech,  and  inarticu- 
late cries  of  the  still  illiterate  Atlantic.  After  the  long 
interval  in  which  it  had  brought  nothing  but  the  moody 
and  often  delirious  mutterings  of  the  sea  stammering 
over  its  alphabet  in  vain,  the  words  '  Canning  to  Glass ' 
must  have  seemed  like  the  first  rational  word  uttered  by 
a  fever-patient  when  the  ravings  had  ceased.  The  exact 
spot  in  the  trackless  ocean  where  that  cable  had  parted 
had  been  found  ;  the  slender  wire  had  been  picked  up, 
although  two  miles  down  under  the  sea;  and  from  the 
great  ship  the  signals  were  being  sent." 

Meanwhile  the  new  cable,  stronger,  lighter,  and  more 
flexible  than  its  predecessors,  had  been  successfully  car- 
ried across  the  Atlantic  by  the  "  Great  P^astern,"  and  was 
in  working  order.  Then  the  ship  went  back,  and,  as 
already  stated,  picked  up  the  broken  end.  How  this 


254  THE  AGE  OF  ELECTRICITY. 

wonderful   feat   of    engineering   was   accomplished,    Mr. 
Field  thus  graphically  tells  :  — 

"After  landing  the  cable  safely  at  Newfoundland,  we 
had  another  task, — to  return  to  mid-ocean,  and  recover 
that  lost  in  the  expedition  of  last  year.  This  achievement 
has  perhaps  excited  more  surprise  than  the  other.  Many, 
even  now  '  don't  understand  it,'  and  every  day  I  am  asked 
how  it  was  done.  Well,  it  does  seem  rather  difficult  to 
fish  for  a  jewel  at  the  bottom  of  the  ocean  two  and  a  half 
miles  deep.  But  it  is  not  so  very  difficult  when  you  know 
how.  It  was  the  triumph  of  the  highest  nautical  and 
engineering  skill.  We  had  four  ships,  and  on  board  of 
them  some  of  the  best  seamen  in  England,  men  who  knew 
the  ocean  as  a  hunter  knows  every  trail  in  the  forest. 
There  was  Captain  Moriarty,  who  was  in  the  '  Agamem- 
non '  in  1857-58.  He  was  in  the  '  Great  Eastern  '  last 
year,  and  saw  the  cable  when  it  broke ;  and  he  and  Cap- 
tain Anderson  at  once  took  their  observations  so  exact 
that  they  could  go  right  to  the  spot.  After  finding  it, 
they  marked  the  line  of  the  cable  by  a  row  of  buoys  ;  for 
fogs  would  come  down,  and  shut  out  sun  and  stars  so  that 
no  man  could  take  an  observation.  These  buoys  were 
anchored  a  few  miles  apart.  They  were  numbered,  and 
each  had  a  flagstaff  on  it  so  that  it  could  be  seen  by  day, 
and  a  lantern  by  night.  Thus  having  taken  our  bearings, 
we  stood  off  three  or  four  miles,  so  as  to  come  broadside 
on,  and  then,  casting  over  the  grapnel,  drifted  slowly 
down  upon  it,  dragging  the  bottom  of  the  ocean  as  we 
went.  At  first  it  was  a  little  awkward  to  fish  in  such  deep 
water ;  but  our  men  got  used  to  it,  and  soon  could  cast  a 
grapnel  almost  as  straight  as  an  old  whaler  throws  a  har- 
poon. Our  fishing-line  was  of  formidable  size.  It  was 
made  of  rope,  twisted  with  wires  of  steel,  so  as  to  bear 
a  strain  of  thirty  tons.  It  took  about  two  hours  for  the 


THE  ELECTRIC  TELEGRAPH.  255 

grapnel  to  reach  the  bottom,  but  we  could  tell  when  it 
struck.  I  often  went  to  the  bow,  and  sat  on  the  rope, 
and  could  feel  by  the  quiver  that  the  grapnel  was  dragging 
on  the  bottom  two  miles  under  us.  But  it  was  very  slow 
business.  We  had  storms  and  calms  and  fogs  and  squalls. 
Still  we  worked  on  day  after  day.  Once,  on  the  17th  of 
August,  we  got  the  cable  up,  and  had  it  in  full  sight  for 
five  minutes,  —  a  long,  slimy  monster,  fresh  from  the  ooze 
of  the  ocean's  bed  ;  but  our  men  began  to  cheer  so  wildly 
that  it  seemed  to  be  frightened,  and  suddenly  broke  away, 
and  went  down  into  the  sea.  This  accident  kept  us  at 
work  two  weeks  longer ;  but  finally,  on  the  last  night  of 
August,  we  caught  it.  We  had  cast  the  grapnel  thirty 
times.  It  was  a  little  before  midnight  on  Friday  that  we 
hooked  the  cable,  and  it  was  a  little  after  midnight  Sunday 
morning  when  we  got  it  on  board.  What  was  the  anxiety 
of  those  twenty-six  hours  !  The  strain  on  every  man's 
life  was  like  the  strain  on  the  cable  itself.  When  finally 
it  appeared,  it  was  midnight :  the  lights  of  the  ship  and 
in  the  boats  around  our  bows,  as  they  flashed  in  the  faces 
of  the  men,  showed  them  eagerly  watching  for  the  cable 
to  appear  in  the  water.  At  length  it  was  brought  to  the 
surface.  All  who  were  allowed  to  approach  crowded  to 
see  it.  Yet  not  a  word  was  spoken  :  only  the  voices  of 
the  officers  in  command  were  heard  giving  orders.  All 
felt  as  if  life  and  death  hung  on  the  issue.  It  was  only 
when  it  was  brought  over  the  bow  and  on  the  deck,  that 
men  dared  to  breathe.  Even  then  they  hardly  believed 
their  eyes.  Some  crept  toward  it  to  feel  of  it,  to  be  sure 
it  was  there.  Then  we  carried  it  along  to  the  electrician's 
room,  to  see  if  our  long-sought- for  treasure  was  alive  or 
dead.  A  few  minutes  of  suspense,  and  a  flash  told  of 
the  lightning  current  set  free.  Then  did  the  feeling  long 
pent  up  burst  forth.  Some  turnt  away  their  heads,  and 


256  THE  AGE   OF  ELECTRICITY. 

wept.  Others  broke  into  cheers,  and  the  cry  ran  from 
man  to  man,  and  was  heard  down  in  the  engine-rooms, 
deck  below  deck,  and  from  the  boats  on  the  water  and 
the  other  ships,  while  rockets  lighted  up  the  darkness  of 
the  sea.  Then  with  thankful  hearts  we  turned  our  faces 
again  to  the  west.  But  soon  the  wind  rose,  and  for  thirty- 
six  hours  we  were  exposed  to  all  the  dangers  of  a  storm 
on  the  Atlantic.  Yet  in  the  very  height  and  fury  of  the 
gale,  as  I  sat  in  the  electrician's  room,  a  flash  of  light 
came  up  from  the  deep,  which,  having  crossed  to  Ireland, 
came  back  to  me  in  mid-ocean,  telling  that  those  so  dear 
to  me,  whom  I  had  left  on  the  banks  of  the  Hudson,  were 
well  and  following  us  with  their  wishes  and  their  prayers. 
This  was  like  a  whisper  of  God  from  the  sea,  bidding  me 
keep  heart  and  hope.  The  '  Great  Eastern  '  bore  herself 
proudly  through  the  storm,  as  if  she  knew  that  the  vital 
cord  which  was  to  join  two  hemispheres  hung  at  her  stern  ; 
and  so,  on  Saturday  the  7th  of  September,  we  brought 
our  second  cable  safely  to  the  shore." 

As  we  all  know,  other  cables  have  since  been  laid  across 
the  Atlantic  with  comparative  ease,  by  the  aid  of  special 
machinery  and  specially  constructed  vessels.  The  French 
cable  between  St.  Pierre  and  Duxbury,  Mass.,  went  into 
operation  in  1869  ;  followed  by  the  direct  cable  between 
Ballinskilligs  Bay,  Ireland,  and  Rye,  N.H.,  via  Nova 
Scotia,  in  1875  ;  and  the  Mackay-Bennett  cable  ten  years 
later. 

The  cable  laid  by  the  "Great  Eastern  "  in  18G5-6G  is 
represented  in  Fig.  107.  The  current  is  conducted  by  a 
strand  of  copper  wires  ;  the  remainder  of  the  cable  serving 
to  secure  insulation,  and  to  protect  it  from  abrasion,  etc. 

The  transmission  of  telegraphic  signals  through  a  long 
submarine  cable  is  a  very  different  matter  from  accom- 
plishing the  same  thing  over  a  land  line  of  similar  length  ; 


THE  ELECTRIC  TELEGRAPH.  257 

and  it  is  therefore  necessary  to  explain,  in  as  simple  terms 
as  possible,  some  of  the  principal  difficulties  encountered, 
and  how  the  cable  is  made  to  operate  in  spite  of  them. 

In  describing  the  invention  of  the  Leyden-jar,  in  an 
earlier  chapter,  we  noted  the  curious  fact,  that,  while  elec- 
tricity cannot  pass  through  an  insulating  substance  such 
as  glass  or  air,  it  can  act  across  the  same  by  induction. 
And  in  the  Leyden-jar  we  have  an  illustration  of  this  ; 
for,  when  a  plus  charge  of  electricity  is  imparted  to  the 
inner  coating,  it  acts  inductively  on  the  outer  coating, 
attracting  a  minus  charge  into  the  face  of  the  outer  coat- 
ing nearest  the  glass,  and  repelling  a  plus  charge  to  the 
outside  of  the  outer  coating,  and  this  through  the  hand 


Fig.  107. 

or  wire  to  the  earth.  After  the  jar  has  acquired  its  full 
charge,  it  will,  as  we  have  already  seen,  retain  it  for  a 
considerable  period  of  time. 

When  a  quantity  of  electricity  flows  through  a  line,  in 
the  form  of  a  current,  the  first  portion  of  the  current  is 
retained  or  accumulated  upon  the  surface  of  the  wire  in 
the  same  way  that  a  charge  is  retained  and  accumulated 
upon  the  surface  of  a  Leyden-jar.  The  wire  itself  answers 
to  one  of  the  conducting  coatings  of  the  jar ;  the  earth, 
or  other  wires  connected  to  earth,  to  the  other  conducting 
coating ;  and  the  air,  to  the  glass  or  separating  di-electric. 
The  quantity  of  electricity  thus  accumulated  depends 
upon  the  length  and  surface  of  the  wire,  upon  its  proxim- 
ity to  the  earth,  and  upon  the  insulating  medium  that  sepa- 


258  THE  AGE  OF  ELECTRICITY. 

rates  it  from  the  earth.  This  power  of  retaining  a  charge 
is  called  the  electro-static  capacity  of  the  circuit. 

The  effect  of  this  accumulation  is  to  hold  back  or  pre- 
vent the  appearance  of  the  first  portion  of  the  current  sent 
at  the  distant  station ;  and,  furthermore,  before  a  current 
in  the  reverse  direction  can  be  sent  through  the  circuit, 
the  whole  of  this  charge  upon  the  wire  must  be  withdrawn 
or  neutralized  before  a  second  charge  of  opposite  sign  can 
be  accumulated  upon  it.  The  result  of  this  is  to  prolong 
the  current  flowing  out  at  the  distant  end. 

In  submarine  cables,  the  conducting  wires  are  separated 
from  the  earth  upon  which  the  cable  rests,  and  the  water 
which  surrounds  it,  simply  by  the  insulating  covering ; 
and  hence  the  whole  cable  becomes  one  huge  Leyden-jar 
of  much  capacity.  The  consequence  is,  that  the  current 
is  retarded  so  much,  that,  unless  the  signals  are  sent  very 
slowly,  they  will  run  together  and  be  illegible.  The  retar- 
dation upon  an  Atlantic  cable  is  about  four-tenths  of  a 
second.  Twenty  dots  per  second  can  be  firmly  and  clearly 
recorded  on  a  short  overground  line,  with  little  induction ; 
while  on  a  long  cable,  not  more  than  two  dots  per  second 
can  be  received. 

Besides  the  difficulties  due  to  retardation,  earth-cur- 
rents varying  in  strength  are  set  up  in  the  cable,  by  rea- 
son of  its  connecting  portions  of  the  earth  which  happen 
to  be  of  different  potentials.  These  were  the  cause  of  the 
strange  signals  which  came  from  the  broken  cable  of  1865  ; 
and  at  times  they  acquire  such  magnitude  as  to  become 
"  electric  storms,"  interrupting  the  circuits  to  such  an 
extent  as  greatly  to  hinder  working,  and  sometimes  en- 
dangering the  safety  of  the  cable  itself.  It  is  necessary, 
therefore,  in  cable  telegraphy,  to  counteract  the  ill  effects 
of  earth-currents,  and  also  to  reduce  to  the  lowest  possi- 
ble point  the  retarding  influence  of  induction  ;  and  the 


THE  ELECTRIC  TELEGRAPH. 


259 


n 

^al 

m^^Mlfc////A    Lx 

\ 
az 

ordinary  apparatus  used  in  telegraphing  upon  land  lines 
becomes  useless  for  this  purpose. 

Two  new  instruments,  not  necessary  upon  land  lines, 
are  therefore  introduced ;  the.  first  being  the  condenser, 
which  prevents  induction,  and  sharpens  the  signals  ;  and 
the  second  being  the  mirror  galvanometer,  or  siphon 
recorder,  which  indicates  or  records  them. 

The  condenser  is  simply  a  modified  form  of  Leyden-jar, 
of  large  surface,  and  constructed  to  have  any  desired  capa- 
city. It  is  usually  made  of  alternate  layers  of  paraffined 
paper  or  mica  and 
tin-foil ;  as  indicat-  1 
ed  in  Fig.  108,  in 
which  the  dark  lines 
a  a1  a2,  b  b1  62,  repre- 
sent tin-foil,  and  the 
shaded  intermediate 
portions,  the  paraf- 
fined paper.  The 
series  a  a1  a?  of  tin- 
foil sheets  are  con- 
nected together,  thus  forming  one  of  the  coatings  of  the 
Leyden-jar ;  and  the  alternating  sheets  b  b1  b2  are  united 
to  form  the  other  coating.  If  we  connect  one  pole  of  a 
battery  to  the  sheets  a  a1  a2,  and  the  other  pole  to  the 
sheets  b  b1  b2,  the  condenser  will  be  charged  with  a  quantity 
of  electricity  depending  upon  the  number  of  battery-cells 
used,  upon  the  surface  of  the  plates  opposed  to  each  other, 
and  upon  the  number  of  plates  in  the  respective  sets.  In 
this  way  condensers  of  any  desired  capacity  can  be  made, 
having  a  charge  varying  from  that  accumulated  upon  one 
mile  of  overground  wire  up  to  that  accumulated  upon  an 
Atlantic  cable.  The  unit  or  standard  of  reference  by 
which  capacity  is  known  is  called  the  microfarad,  and  is 


Fig.  108. 


260  THE  AGE   OF  ELECTRICITY. 

equivalent  to  the  charge  contained  by  about  three  miles  of 
cable. 

The  conventional  mode  of  representing  a  condenser  is 
by  two  parallel  lines  as  a  6:  in  Fig.  109,  from  which  illus- 
tration the  operation  of  the  condenser,  when  applied  to  a 
telegraphic  line,  will  easily  be  understood. 

Let  us  suppose  that  A  B  is  a  cable  crossing  the  Atlantic. 
At  one  end  is  an  ordinary  key  and  battery,  and  at  the 
other  a  condenser  having  one  set  of  its  conducting  plates 
connected  to  the  cable,  and  the  other  set  to  a  galvanometer 
which  in  turn  is  connected  to  earth.  The  circuit  is  evi- 
dently broken  at  the  condenser,  so  that  it  is  impossible 


%J^                   -CaMc 

L 

Credit 

-m^Uct 

k&vy 

^\Eart/i-  coiutcctioit  JEart/v 

Fig.  109. 

for  the  battery  current  to  proceed  directly  to  the  galva- 
nometer ;  but  if  we  depress  the  key,  a  current  flows  from 
the  battery  into  the  cable  to  charge  it.  The  plate  a  of 
the  condenser,  being  thus  charged  in  (say)  positive  elec- 
tricity, attracts  across  the  paraffined  paper  interposed 
between  it  and  the  opposite  plate  6,  electricity  of  opposite 
name,  and  repels  electricity  of  the  same  name,  which 
apparently  passes  to  earth  through  the  galvanometer  in 
the  form  of  a  short  current  or  pulsation.  When  the  key 
is  returned  to  its  normal  position,  the  cable  is  discharged, 
the  positive  charge  on  b  is  released,  and  it  flows  to  earth 
in  the  reverse  direction  through  the  galvanometer,  in  the 


THE  ELECTEIC  TELEGRAPH. 


261 


form  of  a  second  current  or  pulsation.  Thus,  whenever 
we  depress  the  key,  we  affect  the  galvanometer  with  a 
reversal. 

By  using  galvanometers  or  other  receiving  apparatus 
of  the  most  sensitive  character,  which  are  actuated  by 
the  first  appearance  of  the  current,  cables  are  worked 
with  the  smallest  electro-motive  force  ;  and  generally  by 
suitably  determining  the  size  of  the  condenser,  the  num- 
ber of  cells,  and  the  delicacy  of  the  galvanometer,  we 
can  transmit  signals  which  give  the  maximum  speed  with 


the  minimum  expenditure  of  power.  In  practice  the  con- 
densers used  have  a  capacity  equal  to  that  of  about  sev- 
enty miles  of  cable.  From  four  to  ten  cells  of  one  form 
of  Daniell's  battery  furnish  the  current. 

The  receiving  apparatus  is  either  a  mirror  galvanometer 
or  a  siphon  recorder,  —  both  instruments  of  remarkable 
sensitiveness,  devised  by  Sir  William  Thomson.  The 
general  arrangement  of  the  mirror  galvanometer  is  shown 
in  Fig.  110,  where  C  is  a  coil  of  fine  insulated  wire,  sur- 


262  THE  AGE  OF  ELECTRICITY. 

rounding  a  small  magnetic  needle  hung  by  a  silk  fibre, 
and  carrying  a  tiny  mirror  attached  to  it.  The  details 
are  shown  in  the  lower  figure,  where  C  C  are  sections 
through  the  coil.  At  M  is  the  magnet-needle,  carrying 
in  front  of  it  a  small  mirror.  This  needle  is  enclosed 
in  a  small  chamber,  glazed  by  a  lens  6r,  and  inserted  in 
the  hollow  of  the  coil  C.  A  curved  magnet  H  is  sup- 
ported over  the  coil  to  adjust  the  position  of  the  smaller 
magnet  in  the  chamber.  Now  a  ray  of  light  from  a  lamp 
L  in  front  of  the  galvanometer  is  thrown  upon  the  tiny 
mirror,  and  reflected  back  upon  a  white  screen  or  scale 
S.  The  coil  C  is  connected  between  the  end  of  the  con- 
ductor of  the  cable  and  the  earth-plate,  as  in  the  land 
circuit ;  a  condenser,  however,  being  usually  interposed 
between  the  cable  and  the  galvanometer. 

Then  the  signal  currents  in  passing  through  the  coil 
deflect  the  tiny  magnet  hung  within  it ;  and  the  mirror, 
being  carried  by  the  magnet,  throws  the  beam  of  light  off 
in  a  different  direction.  Positive,  or  "  dot,"  currents  are 
arranged  to  throw  the  spot  of  light  toward  the  left  side 
of  the  scale  ;  and  negative,  or  "  dash,"  currents  throw  it 
to  the  right  side.  Thus  the  wandering  of  the  spot  of  light 
on  the  screen,  watchfully  followed  by  the  eye  of  the  clerk, 
is  interpreted  by  him  as  the  message.  Letter  by  letter  he 
spells  it  out,  and  a  fellow-clerk  writes  it  down  word  for 
word. 

Sometimes  the  fellow-clerk  .is  a  lady,  —  frequently  per- 
haps now,  since  the  fair  sex  has  proven  its  ability  to 
manage  the  key, — and  this  circumstance  may  account 
for  the  publication  in  a  scientific  journal,  some  years  ago, 
of  the  following  capital  parody  on  Tennyson's  "  Bugle 
Song:"1  — 

i  By  Professor  J.  Clerk  Maxwell. 


THE  ELECTRIC  TELEGRAPH.       263 

A  LECTURE  ON  THOMSON'S  GALVANOMETER 

Delivered  to  a  Single  Pupil,  in  an  Alcove  with  Drawn  Curtains. 

The  lamp-light  falls  on  blackened  walls, 

And  streams  through  narrow  perforations  ; 
The  long  beam  trails  o'er  pasteboard  scales, 

With  slow  decaying  oscillations. 
Flow,  current,  flow  !  set  the  quick  light  spot  flying  ! 
Flow,  current!  answer,  light  spot  !  flashing,  quivering,  dying. 

Oh,  look  !  how  queer  !  how  thin  and  clear, 

And  thinner,  clearer,  sharper  growing, 
This  gliding  fire  with  central  wire 

The  fine  degrees  distinctly  showing. 
Swing,  magnet,  swing  !  advancing  and  receding  ; 
Swing,  magnet  !  answer,  dearest,  what's  your  final  reading  ? 

O  love  !  you  fail  to  read  the  scale 

Correct  to  tenths  of  a  division  ; 
To  mirror  heaven  those  eyes  were  given, 

And  not  for  methods  of  precision. 
Break,  contact,  break  !  set  the  free  light  spot  flying. 
Break,  contact  !  rest  thee,  magnet  !  swinging,  creeping,  dying. 

This  receiver,  however,  like  the  sounder,  has  the  disad- 
vantage of  leaving  no  permanent  record  ;  and  Sir  William 
Thomson  has  therefore  introduced  his  siphon  recorder  on 
several  long  cables,  —  for  instance,  the  Eastern  Telegraph 
Company's  lines  to  India,  and  the  Anglo-American  Com- 
pany's cables  across  the  Atlantic.  The  principle  of  its 
action  is  just  the  reverse  of  the  mirror  galvanometer.  In 
that  instrument,  a  tiny  magnet  moved  within  a  fixed  coil 
of  wire  ;  in  the  siphon  recorder,  a  light  coil  of  wire  moves 
between  the  poles  of  a  powerful  magnet.  The  signal 
currents  pass  through  the  suspended  coil  to  earth ;  and  in 
doing  so  the  coil  turns  to  left  or  right,  according  as  the 
currents  are  positive  or  negative.  These  movements  of 


264  THE  AGE  OF  ELECTRICITY. 

the  coil  are  communicated  by  a  connecting  thread  to  a 
fine  glass  siphon,  which  is  constantly  spurting  ink  upon 
a  band  of  travelling  paper ;  and  hence  the  trace  of  the 
ink  on  the  paper  follows  and  delineates  the  movements  of 
the  coil.  So  fine  is  the  bore  of  the  siphon,  that  the  ink 
will  not  run  unless  it  is  electrified.  A  specimen  of  the 
message  it  furnishes  is  given  in  Fig.  Ill,  which  represents 
the  alphabet. 

That  some  day  we  shall  be  able  to  transmit  pictures  by 
telegraph,  is  not  without  the  bounds  of  reasonable  possi- 
bility ;  not  drawings  or  designs,  such  as  can  now  be  sent 
by  the  autographic  systems,  but  actual  photographs,  images 
of  things  existing  in  front  of  the  transmitting  instrument, 
so  that  a  person  in  one  place  can  see  what  is  going  on  in 

-n^nFNT/1-^^ 

TA/ir-ylnhA^^ 

Fig.  111. 

another.  The  first  step  in  this  direction  has  already  been 
accomplished  by  Mr.  Shelford  Bidwell,  in  his  exceedingly 
ingenious  telephotograph,  by  means  of  which  it  is  now 
quite  possible  to  transmit  shadows  or  silhouettes.  The 
principle  of  Mr.  Bid  well's  apparatus  is  based  upon  the 
fact  that  the  resistance  of  crystalline  selenium  varies  with 
the  intensity  of  the  light  falling  upon  it.  Its  operation 
depends,  as  in  the  autographic  telegraph,  upon  the  syn- 
chronous movement  of  two  cylinders  at  opposite  ends  of 
the  line,  and  will  be  easily  followed  by  the  aid  of  the 
diagram,  Fig.  112. 

The  transmitting  instrument  consists  of  a  cylindrical 
brass  box,  mounted  upon  but  insulated  from  a  metal  spin- 
dle. The  spindle  is  divided  in  the  middle  ;  and  the  halves, 
while  rigidly  joined  together,  are  insulated  from  each 


THE  ELECTEIC  TELEGRAPH. 


265 


other  by  a  layer  of  wood.  One  of  the  ends  of  the  spin- 
dle has  a  fine  screw-thread  cut  on  it ;  the  other  end  is 
plain.  The  spindle  is  arranged  to  revolve  in  metal  bear- 
ings, one  of  which  is  threaded  so  that  when  the  spindle 
rotates  it  also  has  an  endwise  longitudinal  movement  like 


Fig.  112. 


that  of  the  cylinder  of  the  phonograph.  At  a  point  mid- 
way between  the  ends  of  the  brass  box  mounted  on  the 
spindle,  a  small  hole  is  drilled  ;  and  behind  this  hole  is 
fixed  a  selenium  cell,  the  two  terminals  of  which  are  con- 
nected respectively  to  the  halves  of  the  spindle,  and  the 
bearings  of  this  last  are  connected  electrically  to  binding- 


266  THE  AGE  OF  ELECTRICITY. 

screws  on  the  base  of  the  instrument.  In  the  engraving, 
Y  represents  the  transmitter.  The  hole  in  the  cylinder  is 
at  77,  and  at  S  is  the  selenium  cell. 

The  receiving  instrument  shown  at  X  (Fig.  112)  con- 
tains another  cylinder,  similar  to  that  of  the  transmitter, 
and  mounted  on  a  similar  spindle,  which,  however,  is  not 
divided  nor  insulated  from  the  cylinder.  An  upright  pil- 
lar 7),  fixed  midway  between  the  two  bearings,  and  slight- 
ly higher  than  the  cylinder,  carries  an  elastic  brass  arm 
with  a  platinum  point  P,  which  presses  normally  upon 
the  surface  of  the  cylinder.  To  the  brass  arm,  a  binding- 
screw  is  attached,  and  a  second  binding-screw  in  the  stand 
is  joined  by  a  wire  to  one  of  the  brass  bearings. 

In  operation  the  cylinder  of  the  transmitter  Y  is  brought 
to  its  middle  position,  and  a  picture  not  more  than  two 
inches  square  is  focussed  upon  its  surface  by  means  of  a 
lens.  The  cylinder  of  the  receiver  is  covered  with  paper 
soaked  in  a  solution  of  potassium  iodide. 

The  two  cylinders  are  caused  to  rotate  slowly  and  syn- 
chronously. The  pin-hole  at  H,  in  the  course  of  its  spiral 
path,  will  cover  successively  every  point  of  the  picture 
focussed  upon  the  cylinder ;  and  the  amount  of  light  fall- 
ing at  any  moment  upon  the  selenium  cell  will  be  propor- 
tional to  the  illumination  of  that  particular  spot  of  the 
projected  picture  which  for  the  time  beiug  is  occupied  by 
the  pin-hole.  During  the  greater  part  of  each  revolution, 
the  point  P  will  trace  a  uniform  brown  line  ;  but  when  the 
hole  happens  to  be  passing  over  a  bright  part  of  the  pic- 
ture this  line  is  enfeebled  and  broken.  The  spiral  traced 
by  the  point  is  so  close  as  to  produce,  at  a  little  distance, 
the  appearance  of  a  uniformly  colored  surface ;  and  the 
breaks  in  the  continuity  of  the  line  constitute  a  picture 
which,  if  the  instrument  were  perfect,  would  be  a  mono- 
chromatic counterpart  of  that  projected  upon  the  trans- 


THE  ELECTRIC  TELEGRAPH.  267 

mitter.  Fig.  113  represents  an  image  as  projected  by  a 
magic-lantern  upon  the  transmitter,  and  Fig.  114  the  same 
reproduced  by  the  receiver.  A  selenium  cell  whereby  the 


Fig.  113. 


electrical  resistance  to  the  current  is  varied,  is  also  used 
in  connection  with  the  photophone  hereafter  described. 

Telegraphy  is  by  no  means  confined  to  communication 
between  fixed  stations.     It  is  now  perfectly  possible  to 


Fig.  774. 


communicate  with  express-trains  travelling  at  high  speed, 
and  it  is  not  unlikely  that  some  means  will  be  found  of 
maintaining  telegraphic  communication  with  ships  at  sea. 
Probably  the  earliest  suggestion  of  transmitting  a  current 


268  THE  AGE  OF  ELECTRICITY. 

to  a  moving  vehicle  was  that  made  by  Wright  and  Bain  in 
1842.  These  inventors  proposed  the  ingenious  plan  of 
having  a  pilot-engine  run  some  live  miles  ahead  of  the 
locomotive  of  a  rail  way- train,  and  of  establishing  electri- 
cal communication  between  the  two,  so  that  in  event  of 
any  accident,  such  as  the  derailment  of  the  pilot-engine, 
the  fact  would  be  instantly  known  to  the  driver  of  the 
locomotive.  The  battery  was  to  be  carried  on  the  loco- 
motive ;  and  circuit  was  made  from  the  battery  to  an 
electro-magnet,  and  thence  to  a  continuous  conductor  laid 
between  the  rails,  along  which  contact-springs  on  the  loco- 
motive rubbed.  The  pilot-engine  also  carried  springs  held 
in  contact  with  the  central  conductor ;  and  the  current 
thence  passed  to  a  governor  on  the  pilot,  which,  while  the 
engine  was  in  motion,  was  driven  by  the  wheels.  So  long 
as  the  pilot-engine  was  running  all  right,  tho  governor 
kept  the  circuit  closed ;  but  if  the  engine  stopped,  the 
governor  balls  fell,  opening  the  circuit,  so  de-energizing 
the  electro-magnet  on  the  following  locomotive.  The 
magnet  was  thus  caused  to  release  its  armature,  and  thus 
to  sound  an  alarm,  and  move  a  pointer  on  a  dial  to  the 
word  "Danger."  A  somewhat  analogous  system  exists 
on  several  European  railways,  in  which  a  contact  brush  or 
plate  on  the  locomotive  closes  a  circuit  through  the  rails, 
so  that  the  approach  of  the  train  is  thus  signalled  to  a 
station,  or  the  driver  is  warned,  by  the  sounding  of  an 
alarm,  that  a  switch  before  him  is  not  properly  set.  By 
the  same  means,  the  engine-whistle  may  also  be  blown,  or 
the  brakes  automatically  set  in  operation  to  stop  the  train. 
Two  systems  of  telegraphic  apparatus  have  recently  been 
devised  for  communicating  with  moving  trains.  Phelps's 
arrangement  is  based  on  the  well-known  fact  that  if  two 
wrires  are  extended  parallel,  near  but  not  touching  each 
other,  and  a  current  is  sent  through  one,  a  momentary 


THE  ELECTRIC  TELEGRAPH.  269 

current  is  excited  in  the  other  wire,  opposite  in  direction 
to  that  flowing  in  the  first.  A  telegraph-wire  is  arranged 
in  the  centre  of  the  railway-track,  and  another  wire  is 
attached  to  the  bottom  of  the  railway-car,  with  which  last- 
mentioned  wire  is  connected  a  telegraph-sounder  within 
the  car.  Whenever  an  electrical  signal  is  sent  through 
the  track  telegraph  wire,  it  produces  by  induction  a  cor- 
responding current  in  the  wire  attached  to  the  car,  and 
this  current  works  the  sounder,  thus  delivering  the  mes- 
sage. It  matters  not  how  fast  the  train  may  be  moving, 
if  the  wire  on  the  bottom  of  the  car  is  brought  within  a 
short  distance  of  the  telegraph  or  track  wire,  any  strong 
electric  impulses,  such  as  telegraph  signals,  that  are  pass- 
ing along  the  track  wire,  will  be  taken  up  by  induction  by 
the  car  wire,  and  delivered  by  the  sounder ;  and,  vice 
versa,  when  the  operator  on  the  moving  car  operates  the 
lever  of  his  telegraph  instrument,  and  sends  electrical  im- 
pulses or  messages  through  the  wire  that  hangs  below  the 
floor  of  the  car,  these  impulses  will  be  taken  up  by  induc- 
tion by  the  track  wire,  and  conveyed  to  .the  sounding 
instrument  of  the  railway-station.  By  this  system  com- 
munication has  been  successfully  maintained  with  a  train 
running  forty  miles  per  hour. 

In  another  system  devised  by  Edison  and  others,  the 
induction  takes  place  between  the  wires  strung  in  the 
usual  way  on  poles  beside  the  track,  and  the  metal  roofs 
of  the  cars  which  are  electrically  connected  together.  An 
insulated  wire  runs  from  the  roof  of  the  telegraphing  car, 
to  a  switch  at  the  operator's  desk  ;  and  by  means  of  this 
switch  the  circuit  may  be  completed  through  a  receiving 
or  a  transmitting  instrument.  The  receiver  may  either  be 
an  ordinary  telephone,  or  a  pair  may  be  used  and  held  to 
the  ears  somewhat  after  the  manner  of  ear-muffs.  After 
coming  from  the  receiver,  the  wire  is  carried  under  the 


270  THE  AGE  OF  ELECTRICITY. 

car,  and  connected  to  a  strip  of  copper  which  is  pressed 
against  a  copper  cylinder  on  one  of  the  axles  by  means  of 
a  spring,  thus  giving  a  ground  connection  by  the  axle  and 
wheel.  When,  however,  a  message  is  to  be  transmitted, 
the  switch  connects  the  roof  to  the  secondary  wire  of  an 
induction  coil,  with  the  primary  of  which  a  battery,  a 
Morse  key,  and  a  vibrating  circuit-breaker  are  in  circuit. 
When  the  current  is  established,  the  vibrator,  which  con- 
tains a  metallic  reed,  is  thrown  into  rapid  movement ;  the 
free  end  of  the  reed  at  each  vibration  striking  against  a 
button,  and  so  sharply  making  and  breaking  the  circuit 
into  a  great  number  of  waves  or  pulsations.  These  pul- 
sations in  the  primary  coil  induce  currents  of  high  poten- 
tial in  the  secondary  coil,  which,  so  to  speak,  charge  the 
roof  as  if  it  were  one  plate  of  a  condenser.  The  wires 
on  the  poles  thus  become  charged  by  induction,  as  the 
opposite  plate  of  a  condenser  is  charged,  through  the  inter- 
vening air ;  and  as  this  charge  is  governed  by  the 
manipulation  of  the  Morse  key,  which  throws  the  vibrator 
into  and  out  of  action,  dots  and  dashes  of  the  Morse 
alphabet  can  be  signalled. 

New  applications  of  the  telegraph  are  constantly  being 
invented.  We  are  only  at  the  very  beginning  of  its  utili- 
zation in  the  affairs  of  every-day  life,  and  yet  its  developed 
capabilities  are  bewildering.  There  is  little  exaggeration 
in  the  statement  that  one  can  sit  at  home,  and  "steer  a 
torpedo  boat  in  New- York  harbor,  or  ring  the  bells  in 
Boston,  or  play  the  organ  in  St.  Peter's,  or  explode  a 
mine  in  China,  or  write  a  letter  on  the  desk  of  a  cor- 
respondent in  Constantinople,"  —and  perhaps,  in  the 
future,  talk  to  a  friend  in  Australia,  and  even  see  him 
face  to  face. 

From  forty  miles  in  1844,  the  total  length  of  telegraph- 
wires  in  the  United  States  has  increased  to  671,000  miles 


THE  ELECTEIC  TELEGRAPH.  271 

in  1886  :  enough  to  extend  to  the  moon  and  back  again, 
and  then  go  nine  times  around  the  earth.  Nearly  two 
millions  of  miles  of  wire  form  an  iron  network  over  the 
globe ;  and  the  great  army  of  the  telegraphers  numbers 
over  three  hundred  thousand  souls. 


272  THE  AGE  OF  ELECTRICITY. 


CHAPTER    XII. 

THE    SPEAKING   TELEPHONE. 

THE  principle  underlying  all  forms  of  apparatus  for 
transmitting  intelligence  between  distant  points,  by  the 
aid  of  electricity,  is  to  cause  certain  mechanical  motions 
produced  at  one  point  to  be  imitated  at  the  other.  And 
these  mechanical  motions  may  range  from  the  slow  move- 
ment of  a  telegraph-key  worked  by  the  human  hand,  to 
the  very  rapid  and  complex  vibrations  of  the  air  which  the 
ear  and  brain  translate  into  the  sensation  of  sound.  The 
motion  of  the  telegraph-key  is  copied  by  the  motion  of 
the  sounder  armature,  or  that  of  the  recording  stylus ;  in 
autographic  telegraphy,  the  movement  of  the  point  which 
traces  the  design  is  imitated  by  that  of  the  point  which  re- 
produces the  same  ;  and  the  various  synchronic  systems 
have  for  their  object  the  exact  duplication  at  the  separated 
stations  of  definite  mechanical  movements  occurring  at 
the  same  rate  in  the  same  time. 

The  simplest  way  of  transmitting  mechanical  motion 
between  distant  points  is  by  means  of  some  solid  body 
extending  between  them.  The  connecting-rod  of  an  en- 
gine transmits  movement  from  piston-rod  to  fly-wheel ;  by 
means  of  belts,  we  can  cause  one  rotating  shaft  to  move 
another  at  a  considerable  distance  away ;  by  pulling  a 
cord  or  wire  in  one  part  of  a  house,  we  can  ring  a  bell  at 
another.  In  all  of  these  instances,  the  whole  of  the  com- 


THE  SPEAKING   TELEPHONE.  273 

municating  body  —  whether  it  be  rod  or  belt  or  wire  — 
moves  simultaneously. 

Motion,  however,  may  also  be  transmitted  by  means  of 
waves  or  pulsations  in  the  communicating  body,  which 
then  does  not  move  as  a  whole.  In  such  case,  the  move- 
ment is  first  imparted  to  the  particles  of  the  body  nearest 
the  source.  These  are  set  vibrating,  or  swinging  to  and 
fro ;  and  in  so  travelling  they  communicate  their  motion 
to  a  succeeding  set  of  particles,  which  in  turn  swing  or 
vibrate ;  these,  again,  in  turn  actuate  the  particles  next  in 
advance  ;  and  so  the  vibration  or  wave  travels  from  one 
end  of  the  body  to  the  other.  This  is  called  wave  or 
vibratory^ motion.  Light,  for  example,  is  propagated  by 
motion  of  this  kind,  in  an  assumed  luminiferous  ether ; 
heat,  sound,  and  probably  electricity,  by  wave-motions  in 
the  molecules  of  matter.  We  see  this  vibratory  motion 
constantly  at  work  in  waves  on  water. 

When  any  body  vibrates  in  air  or  water,  or  any  material 
substance,  the  air  or  other  substance  is  set  in  motion, 
and  the  waves  are  propagated  farther  and  farther  from 
the  impelling  source,  until  finally  their  energy  becomes 
exhausted.  This  movement  of  the  air,  on  reaching  the 
human  ear,  causes  the  sensation  of  sound,  provided  it  is 
competent  to  affect  the  mechanism  of  hearing.  It  has 
been  determined  that  the  ear  cannot  perceive  sounds  when 
the  number  of  vibrations  is  less  than  sixteen,  or  more  than 
thirty-two  thousand,  per  second  ;  but  the  limits  of  hear- 
ing vary  greatly.  If  the  vibrating  body  be  in  the  open 
air,  the  impulses  spread  equally  on  all  sides  around ; 
sometimes  having  great  mechanical  force,  as  when  an 
explosion  of  dynamite  shatters  walls  even  at  a  consider- 
able distance.  So  also  the  air  is  competent  to  carry  very 
minute  vibrations  ;  as,  for  instance,  those  which,  as  we 
shall  see  hereafter,  cause  the  different  quality  of  human 


274  THE  AGE  OF  ELECTRICITY. 

voices.  In  order  to  prevent  the  diminution  in  intensity  of 
the  air-waves  caused  by  the  vibration  of  our  vocal  organs 
in  speaking,  clue  to  their  spreading  in  all  directions,  the 
speaking-tube  is  employed ;  and  this  is  the  most  common 
mode  of  carrying  the  voice  between  distant  points.  Here 
the  column  of  air  is  enclosed  in  a  pipe,  and  the  pulsations 
are  passed  on  from  end  to  end,  almost  without  loss,  over 
short  distances. 

Solids  such  as  wood,  metal,  the  earth,  and  liquids  such 
as  water,  are  much  better  conductors  of  sound  than  air  or 
other  gases.  A  faint  scratch  of  a  pin  on  a  long  board  is 
very  easily  heard  through  the  board  many  feet  away,  even 
though  it  may  not  be  audible  through  the  air  to  the  per- 
son making  it.  Savages  often  discover  the  proximity  of 
enemies  or  of  prey  by  applying  an  ear  to  the  ground,  and 
hearing  the  tread.  The  mutterings  of  earthquakes,  due 
to  subterranean  explosions  or  upheavals,  are  heard  through 
amazing  distances  of  earth.  The  velocity  of  sound  in 
air  is  about  1,120  feet  per  second  ;  in  water,  about  four 
times,  and  in  metals  from  four  to  sixteen  times,  as  great. 

The  idea  of  transmitting  sounds  of  the  voice  through 
solid  conductors  is  known  to  date  back  to  1G67.  At  that 
date  Dr.  Robert  Hooke  wrote :  "It  is  not  impossible  to 
hear  a  whisper  at  a  furlong's  distance,  it  having  already 
been  done  ;  and  perhaps  the  nature  of  the  thing  would  not 
make  it  more  impossible  though  that  furlong  should  be  ten 
times  multiply 'd.  And  though  some  famous  authors  have 
affirmed  it  impossible  to  hear  through  the  thinnest  plate  of 
muscovy  glass  :  yet  I  know  a  way  by  which  it  is  easie 
enough  to  hear  one  speak  through  a  wall  a  yard  thick. 
It  has  not  yet  been  thoroughly  examin'd  how  far  otacous- 
ticons  may  be  improv'd  nor  what  other  wayes  there  may 
be  of  quick'ning  our  hearing  or  conveying  sound  through 
other  bodies  than  the  air  :  for  that  that  is  not  the  only  me- 


THE  SPEAKING    TELEPHONE.  275 

dium  I  can  assure  the  reader,  that  I  have  by  the  help  of  a 
distended  wire  propagated  the  sound  to  a  very  considerable 
distance  in  an  instant  or  with  as  seemingly  quick  a  motion 
as  that  of  light,  at  least  incomparably  quicker  than  that 
which  at  the  same  time  was  propagated  through  the  air, 
and  this  not  only  in  a  straight  line  or  direct  but  in  one 
bended  at  many  angles." 

In  1819  Sir  Charles  Wheatstone  invented  his  magic 
lyre,  and  in  1831  exhibited  it  at  the  Polytechnic  Institution 
in  London.  He  called  it  the  telephone,  thus  inventing  the 
name.  Performers  on  various  instruments  were  placed  in 
the  basement  of  the  building,  and  the  sounds  which  they 
produced  were  conducted  by  solid  rods  through  the  princi- 
pal hall,  in  which  they  were  inaudible,  to  sounding-boards 
in  a  concert- room  on  an  upper  floor,  where  the  music  was 
heard  by  the  audience  precisely  as  if  it  were  being  per- 
formed there.  It  is  related,  that,  shortly  after  Sir  Charles 
Wheatstone  had  invented  the  above  device,  he  invited  a 
distinguished  foreign  musician  —  a  noted  performer  on 
the  violoncello  —  to  dine  with  him.  In  order  to  surprise 
his  guest,  he  suspended  a  violoncello  in  his  entrance-hall, 
arranging  in  contact  with  it  a  concealed  rod  which  com- 
municated with  a  like  instrument  in  another  room.  On 
the  arrival  of  the  visitor,  he  was  left  alone  in  the  hall, 
and  naturally  his  attention  was  at  once  attracted  by  the 
strains  of  music  apparently  coming  from  no  visible  source, 
yet  clearly  being  produced  in  the  same  apartment.  Finally 
he  traced  them  to  the  instrument  on  the  wall,  examined 
it  critically,  could  find  no  reason  for  them ;  and  then  as 
if  struck  with  sudden  terror,  with  a  cry  of  dismay,  the 
affrighted  musician  rushed  out  of  the  house.  Nothing 
could  convince  him  that  the  instrument  was  not  bewitched, 
nor  induce  him  to  trust  himself  again  in  its  proximity. 

Meanwhile  there  had  been  known  —  probably  since  time 


276  THE  AGE  OF  ELECTRICITY. 

immemorial,  for  the  Chinese  are  said  to  have  used  it  ages 
ago  —  an  apparatus  called  the  "lover's  telegraph,"  in 
which  sounds  of  the  voice  were  transmitted  between  dis- 
tant points,  over  a  stretched  string  or  wire.  The  contriv- 
ance will  easily  be  understood  from  Fig.  115,  in  which  A 
and  B  are  hollow  cylinders,  usually  of  tin,  each  having 
one  end  covered  with  a  piece  of  membrane.  The  string 
is  fastened  at  each  extremity  to  the  centres  of  the  mem- 
branes, and  is  strained  taut  when  the  instrument  is  used. 
Words  spoken  into  one  cylinder  are  very  clearly  heard  by 
a  listener  at  the  open  end  of  the  other.  Just  how  and 
why  this  little  device  operates,  is  by  no  means  clear. 


Fig.  115. 

The  membrane  spoken  to,  however,  vibrates  correspond- 
ingly to  the  air-waves  made  by  the  speaker's  voice  ;  and 
probably  the  impulses  passing  over  the  string  move  the 
other  membrane  so  that  it  copies  the  motions  of  the  first, 
and  thus  becomes  a  body  vibrating  in  a  particular  way, 
an,d  competent  in  turn  to  make  air- waves  which  the  ear 
recognizes  as  speech,  just  as  if  the  vocal  organs  of  the 
original  speaker  had  been  transported  to  the  distant  end  of 
the  line.  We  say  "  probably,"  because  it  is  by  no  means 
certain  that  this  happens  ;  and,  in  fact,  there  is  a  great  deal 
to  be  discovered  about  the  instrument.  Whatever  may  be 
the  true  reason,  it  is  certain  that  speech  is  very  clearly 
transmitted  and  reproduced ;  and  in  its  more  improved 
modern  forms  the  device  now  known  as  the  acoustic  tele- 


THE  SPEAKING    TELEPHONE.  277 

phone  is  much  more  efficient  for  short  lines,  where  the  wire 
can  be  suspended  clear  of  other  objects,  than  any  telephone 
depending  on  electricity,  which  of  course  this  does  not. 

In  tracing  the  history  of  the  telegraph,  we  have  noted 
some  of  the  early  attempts  made  to  produce  sound-signals 
at  the  far  end  of  the  line.  Prior  to  Morse's  invention,  it 
was  difficult  to  record  the  operation  of  the  current ;  and 
to  rely  on  visual  signals  was  to  depend  on  the  watchfulness 
of  the  receiving  operator  at  all  times.  One  inventor  pro- 
posed explosions  which  would  very  effectually  alarm  the 
sleepiest  attendant ;  another  rang  bells,  and  so  on.  For 
several  years  succeeding  the  introduction  of  Wheatstone's 
needle  telegraph  in  England,  this  problem  was  widely 
studied.  In  1837  Professor  Page  of  Washington  discov- 
ered that  an  electro-magnet  when  magnetized  and  demag- 
netized gives  forth  a  sound  ;  and  when  the  current  through 
its  coil  is  rapidly  established  and  broken,  these  sounds 
may  succeed  each  other  with  sufficient  velocity  to  produce 
a  musical  tone,  —  the  pitch  of  which  will  depend  upon 
the  number  of  times  the  sound  is  produced  per  second. 
Page's  discovery  was  made  the  basis  of  further  investiga- 
tions by  Wertheim  and  others. 

In  1854  M.  Charles  Bourseul  published  one  of  those 
curious  speculations  which  have  so  often  foreshadowed 
remarkable  inventions.  It  is  very  frequently — sometimes 
too  frequently  —  the  case,  that  the  imagination  of  the 
reader,  after  the  event,  causes  him  to  detect  in  these  prior 
records  the  recital  of  ideas  never  broached  until  long 
afterwards  ;  just  as  one  can  find  in  Milton  such  lines  as 
these :  — 

"  When  with  one  virtuous  touch 
The  arch-chymic  sun,  so  far  from  us  remote, 
Produces  with  terrestrial  humor  mixed 
Here  in  the  dark,  so  many  precious  things 
Of  color  glorious,  and  effect  so  rare,"  — 


278  THE  AGE  OF  ELECTRICITY. 

and  thence  argue  that  photography  must  have  been  known 
in  Milton's  time.  Bourseul,  however,  wrote  much  less 
oracularly  than  is  common  in  the  circumstances.  He 
says,  "  I  have,  for  example,  asked  myself  whether  speech 
itself  may  not  be  transmitted  by  electricity ;  in  a  word, 
if  what  is  spoken  in  Vienna  may  not  be  heard  in  Paris. 
The  thing  is  practicable  in  this  way.  We  know  that 
sounds  are  made  by  vibrations,  and  are  adapted  to  the 
ear  by  the  same  vibrations  which  are  reproduced  by  the 
intervening  medium.  But  the  intensity  of  the  vibrations 
diminishes  very  rapidly  with  the  distance  ;  so  that  it  is, 
even  with  the  aid  of  speaking-tubes  and  trumpets,  impossi- 
ble to  exceed  somewhat  narrow  limits.  Suppose  that  a 
man  speaks  near  a  movable  disk,  sufficiently  flexible  to 
lose  none  of  the  vibrations  of  the  voice,  that  this  disk  al- 
ternately makes  and  breaks  the  current  from  a  battery :  you 
may  have  at  a  distance  another  disk  ivhich  will  simulta- 
neously execute  the  same  vibrations.  It  is  true  that  the 
intensity  of  the  sounds  produced  will  be  variable  at  the 
point  of  departure  at  which  the  disk  vibrates  by  means  of 
the  voice,  and  constant  at  the  point  of  arrival  where  it 
vibrates  by  means  of  electricity ;  but  it  has  been  shown 
that  this  does  not  change  the  sounds.  It  is,  moreover, 
evident  that  the  sounds  will  be  reproduced  at  the  same 
pitch.  The  present  state  of  acoustic  science  does  not 
permit  us  to  declare  a  priori  if  this  will  be  precisely  the 
case  with  the  human  voice.  The  mode  in  which  these 
syllables  are  produced  has  not  yet  been  sufficiently  inves- 
tigated. It  is  true  that  we  know  that  some  are  uttered 
by  the  teeth,  others  by  the  lips,  and  so  on  ;  but  this  is 
all. 

"  However  this  maybe,  observe  that  the  syllables  can 
only  reproduce  upon  the  sense  of  hearing  the  vibrations 
of  the  intervening  medium :  reproduce  precisely  these  vi- 


THE  SPEAKING    TELEPHONE.  279 

brat  ions,  and  you  will  reproduce  precisely  these  syllables. 
...  It  need  not  be  said  that  numerous  applications  of 
the  highest  importance  will  immediately  arise  from  the 
transmission  of  speech  by  electricity.  Any  one  who  is 
not  deaf  and  dumb  may  use  this  mode  of  transmission, 
which  would  require  no  apparatus  except  an  electric  bat- 
tery, two  vibrating  disks,  and  a  ivire." 

There  can  be  no  question  as  to  the  remarkable  knowl- 
edge possessed  by  the  writer,  especially  as  indicated  by  the 
words  Italicized.  Bourseul  had  undoubtedly  realized  the 
fundamental  principle,  that,  in  order  to  reproduce  sounds 
in  air  at  the  distant  end  of  a  wire,  the  apparatus  must  be 
competent  to  copy  the  vibrations  which  originally  were 
imposed  on  the  sending  apparatus  by  the  voice.  He 
clearly  saw,  however,  that  his  conception  was  by  no  means 
adequate  to  the  object. 

Thus  two  ideas  were  well  established  before  1860  :  first, 
that  it  might  be  possible  to  cause  an  object  to  vibrate 
by  the  voice,  so  as  to  make  and  break  a  current  passing 
upon  a  telegraph-line,  causing  in  that  current  pulsations 
corresponding  in  frequency  with  the  vibrations  due  to  the 
sounds  produced  ;  and,  second,  that  when  a  current,  rap- 
idly interrupted,  entered  the  coils  of  an  electro-magnet, 
the  magnet  would  yield  a  sound  which  would  be  a  musical 
tone  depending  for  its  pitch  upon  the  number  of  times  the 
current  was  interrupted  per  second. 

But  Bourseul,  who  proposed  the  making  and  breaking 
of  the  current  by  the  disk  moved  by  the  voice,  apparently 
knew  nothing  about  reproducing  the  tone  by  the  electro- 
magnet ;  and  Page,  who  invented  "galvanic  music,"  knew 
nothing  about  interrupting  the  current  by  voice-controlled 
mechanism.  And  this  brings  .us  to  the  remarkable  history 
of  Philipp  Reis,  —  the  man  in  whom  his  Fatherland  persists 
in  recognizing  the  true  inventor  of  the  speaking  telephone. 


280  THE  AGE  OF  ELECTRICITY. 

A  tablet  so  inscribed  marks  the  house  in  which  he  was 
born,  and  a  like  inscription  is  graven  on  the  monument 
publicly  reared  in  his  honor. 

Johann  Philipp  Reis  was  born  at  Gelnhaussen  in  the 
principality  of  Cassel,  Germany,  in  1834.  His  father,  a 
master  baker,  gave  him  a  good  education,  and  finally  ap- 
prenticed him  to  a  color-manufacturer.  A  natural  taste 
for  scientific  subjects  led  to  his  becoming  in  1851  a  mem- 
ber of  the  Physical  Society  of  Frankfort,  where  he  began 
the  studies  which  subsequently  led  him  to  take  up  teaching 
as  a  profession.  In  1858  Reis  became  a  tutor  in  Gamier' s 
Institution  for  Boys  at  Friedrichsdorf,  and  this  was  his 
position  in  life  when  he  began  his  electrical  experiments. 
The  instrument  which,  in  probable  ignorance  of  Wheat- 
stone's  long-prior  use  of  the  name,  he  called  u  das  Tele- 
plion,"  was  devised  in  I860  ;  and  he  lectured  on  it  publicly 
at  various  times  between  1861  and  1864.  Between  those 
who  misunderstood  it  entirely,  and  those  who,  like  Pog- 
gendorf,  refused  even  to  publish  Reis'  memoir  on  the 
apparatus  because  the  transmission  of  speech  by  electricity 
was  regarded  as  too  chimerical  for  serious  consideration, 
the  invention  met  with  little  or  no  appreciation.  Various 
professors  lectured  upon  it,  and  several  instruments  were 
sold  to  physical  laboratories  throughout  the  world  ;  but 
outside  of  Reis  himself  and  a  few  intimate  friends,  it  is 
doubtful  if  any  one  regarded  the  invention  as  more  than 
a  scientific  curiosity  —  creditable,  of  course,  to  its  origina- 
tor, but  by  no  means  giving  him  any  title  to  fame.  Reis 
lived  until  1874,  but  his  labors  upon  his  telephone  appear 
to  have  ended  ten  years  before  his  death.  His  opponents 
say,  that,  having  failed  to  transmit  speech  by  his  appara- 
tus, he  perforce  dropped  it ;  his  friends,  that  he  laid  it 
aside  partly  from  ill  health,  but  mainly  from  a  feeling  of 
deep  disappointment  because  of  the  lack  of  appreciation 


THE  SPEAKING    TELEPHONE.  281 

which  it  encountered  among  his  brother  scientists.  It 
does  not  appear  that  he  made  any  other  inventions  ;  and 
to  his  early  decease  may  perhaps  be  attributed  the  fact 
that  he  rose  to  nothing  higher  than  an  humble  tutorship. 
What  with  ill  health,  and  the  sense  of  many  rebuffs  prey- 
ing upon  him,  his  life,  he  says  in  his  autobiographical 
notes,  was  one  of  "labor  and  sorrow  ;  "  yet  there  is  little 
in  Reis'  history  to  support  this  conclusion,  especially  when 
contrasted  with  the  records  of  the  privations  and  hardships 
which  have  fallen  to  the  lot  of  many  of  the  world's  great- 
est inventors.  Reis  does  not  appear  ever  to  have  suffered 
from  poverty,  nor  to  have  depended  in  any  sense  upon 
the  success  of  his  invention  for  support.  He  was  able  to 
leave  a  useful  trade,  to  prosecute  studies  which  fitted  him 
for  his  own  chosen  occupation, —  teaching,  —  and  equally 
able  to  secure  a  permanent  position  as  a  tutor,  which 
afforded  him  not  only  leisure  for  the  prosecution  of  his 
investigations,  but  congenial  associates  who  have  testified 
to  their  appreciation  of  his  efforts.  Contrast  this  with  the 
long  penury  and  want  of  Howe,  of  Whitney,  of  Henry 
Cort,  and  a  host  of  others,  and  Reis'  lot  in  life  was 
comparatively  enviable. 

Reis,  moreover,  lacked  that  peculiarity  of  inventors,  — 
persistence.  It  is  enough  to  say,  that,  if  he  had  the 
knowledge  of  the  immense  importance  of  his  invention 
which  is  now  ascribed  to  him,  his  failure  to  prosecute  it 
for  the  last  ten  years  of  his  life  —  between  the  ages  of 
thirty  and  forty,  when  the  enthusiasm  of  youth  has  hardly 
begun  to  be  tempered  with  the  conservatism  which  comes 
with  later  years  —  is  simply  phenomenal.  Most  inventors 
imbued  with  a  great  thought,  like  Stephen  Gray,  never 
relinquish  it  until  death  ;  and  in  the  face  of  suffering  and 
poverty,  their  devotion  to  their  ideals  too  often  results  in 
sacrifices  and  self-denials  far  greater  than  those  which, 


282  THE  AGE   OF  ELECTRICITY. 

when  otherwise  directed,  have  provoked  the  admiration 
of  the  world,  and  made  men  heroes. 

Reis  devised  several  forms  of  telephonic  instruments, 
including  many  merely  experimental,  and  substantially 
embodied  in  more  complete  devices.  His  manipulative 
skill  was  of  a  very  low  order.  He  had  an  actual  poverty 
of  resource  in  adapting  means  to  ends.  He  differed  from 
the  generality  of  inventors,  who  construct  means  first,  and 
evolve  theories  afterwards. 

In  order  to  understand  what  Reis  did,  it  is  necessary  to 
recall  a  few  salient  facts  relative  to  sound,  to  some  of 
which  reference  has  already  been  made. 

Sound,  as  we  have  seen,  is  due  simply  to  wave-motion 
or  vibration  of  the  air,  or  other  material  medium  in  which 
the  motion  is  propagated.  The  waves  or  vibrations  may 
differ  in  length,  in  frequency,  or  in  shape.  We  can  always 
see  on  the  ocean  long  waves  and  short  waves,  waves  fol- 
lowing each  other  rapidly  or  slowly,  and  waves  smooth 
and  glassy,  like  the  ground-swell,  or  broken  up  on  their 
surfaces  into  multitudinous  smaller  waves,  as  when  the 
wind  blows  strongly.  The  length  of  a  sound-wave  — 
that  is,  the  path  over  which  the  air-particles  swing  to  and 
fro — determines  the  loudness  of  the  resulting  sound;  the 
frequency  of  the  waves,  the  pitch  of  the  sound,  a  higher 
or  lower  note  on  the  musical  scale  ;  and  the  shape  of  the 
wave  governs  the  quality  or  timbre  of  the  sound,  upon 
which  depends  the  difference  between  the  sound  of  a  flute 
and  that  of  a  violin,  between  the  sweet  note  of  the  night- 
ingale and  the  screech  of  a  peacock,  and  between  articu- 
late speech  and  a  groan  or  a  howl  or  a  moan. 

We  can  thus  form  some  notion  of  what  a  complex  thing 
an  air-wave  produced  by  speech  is.  We  are  constantly 
raising  and  lowering  our  voices,  and  hence  there  are  waves 
of  all  conceivable  lengths.  We  are  also  constantly  using 


THE  SPEAKING   TELEPHONE.  283 

different  notes  of  the  musical  scale,  and  modulations  of 
all  sorts,  even  in  talking ;  and  so  the  waves  are  set  in 
motion  by  our  vocal  apparatus  with  all  degrees  of  fre- 
quency. And,  finally,  we  articulate,  we  use  inflections  ; 
our  voice  is  rough  or  harsh,  or  sweet  and  melodious  ;  and 
so  imposed  on  the  air-waves  are  all  sorts  of  ripples,  smaller 
waves,  which  contort  and  change  their  shapes. 

It  is  not  difficult  to  conceive  that  the  simple  frequency 
of  the  waves  of  sound  may  set  a  disk  free  to  be  moved, 
—  like  a  drum-head, — vibrating  with  like  frequency  ;  so 
that,  as  Bourseul  points  out,  we  can  cause  that  disk  to 
make  or  break  an  electrical  current  as  many  times  per 
second  as  there  are  air-vibrations  in  that  time.  But  when 
the  same  disk  is  made,  by  the  same  waves,  to  vibrate  over 
a  long  path  or  a  short  path,  and  even,  at  different  periods 
of  its  motion,  to  travel  slower  or  faster  for  infinitesimal 
intervals  of  time,  corresponding  to  the  little  waves  which 
articulation  imposes  on  the  large  ones,  how  are  we  to 
modify  the  electric  current  by  these  motions?  Merely 
making  and  breaking  the  current  will  simply  cause  it  to 
set  Page's  needle,  at  the  other  end  of  a  line,  into  vibra- 
tion as  many  times  per  second  as  the  current  is  made  and 
broken  per  second  ;  and,  if  the  "  makes  "  and  "  breaks  " 
are  fast  enough,  the  needle  will  sing  in  its  own  voice  a 
note  of  corresponding  pitch.  There  will  be  no  variations 
in  loudness,  and  the  sound  produced  will  not  resemble  the 
sound  transmitted,  except  that  both  will  be  pitched  on 
the  same  note.  The  needle  will  sound  just  the  same  when 
the  same  note  is  sung  to  the  circuit-breaking  disk  by  a 
Patti,  or  a  stearn-whistle,  — just  the  same  if  the  sound  be 
produced  by  the  most  silvery-tongued  of  orators,  or  a 
hyena.  Nothing  but  the  pitch  of  the  sound,  nothing  but 
the  succession  of  vibrations  making  that  pitch,  will  modify 
the  current. 


284  THE  AGE  OF  ELECTRICITY. 

Heis,  as  we  have  said,  knew  all  about  these  curious  and 
Complex  characteristics  of  the  sound-wave.  He  was  a 
professor  of  physics,  and  it  was  his  business  to  know 
them.  Beyond  this  he  knew  of  an  ingenious  little  piece 
of  apparatus  called  the  phonautograph,  which  consisted  of 
a  cylinder,  over  one  end  of  which  was  stretched  a  sheet 
of  membrane  ;  to  the  membrane  a  little  stylus  was  fas- 
tened, the  free  end  of  which  rested  on  a  rotating  cylinder 
covered  with  lamp-black.  When  any  one  talked  into  the 
phonautograph,  the  membrane  diaphragm  vibrated ;  and 
when  the  cylinder  was  turned,  and  at  the  same  time  moved 
lengthwise,  the  little  stylus  fastened  to  the  membrane 
traced  queer  curves  and  sinuosities  characteristic  of  the 
sounds  produced  :  and  so,  in  fact,  in  this  way  the  sounds 
wrote  down  their  own  peculiarities. 

Now  we  can  see  the  problem  which  was  before  Reis. 
Bourseul  had  proposed  to  make  the  thing  which  under  the 
influence  of  the  current  was  to  vibrate,  and  so  reproduce 
the  sounds  at  the  receiving  end,  copy  the  movements  of 
the  thing  vibrated  by  the  voice  at  the  sending  end.  Reis 
knew  how  complex  the  vibrations  were,  and  equally  knew 
that  a  stretched  membrane  would  follow  them,  and  could 
be  set  in  motion  by  them.  But  how  was  the  current  to  be 
controlled  by  the  membrane,  so  that  it  in  turn  would  gov- 
ern something  else  far  off  at  the  other  end  of  a  wire,  and 
make  it  copy  the  movements  of  that  membrane  ?  Let  the 
reader  think  for  a  moment  on  the  enormous  difficulty  in- 
volved. Not  only  must  the  current  be  modified  in  some 
way,  to  copy  the  frequency  and  amplitude  (length)  of  the 
air-vibrations,  but  every  little  minor  peculiarity  of  the  vi- 
brations superimposed  on  those  vibrations, — these  over- 
vibrations,  these  ripples  on  the  large  waves,  often  occur- 
ring at  the  rate  of  tens  of  thousands  per  second.  Imagine 
a  mechanism  made  by  human  hands  capable  of  doing  this  ! 


THE  SPEAKING   TELEPHONE. 


285 


Reis  may  be  said  to  have  exposed  the  tremendous  ob- 
stacles which  lay  in  the  path  of  any  one  who  should  attempt 
to  carry  into  practice  Bourseul's  theory  ;  and  for  this  he  is 
entitled  to  lasting  credit.  Knowing  what  obstacles  there 
are,  is  next  best  to  knowing  how  to  surmount  them.  But 
the  first  does  not  involve  invention ;  the  second  does. 

Reis  began  by  carving  a  model  of  a  human  ear  out  of  a 
piece  of  oak.  Figs.  116  and  117 


show   it   in 


and    section. 


Fig.  116. 


Fig.  117. 


Through  this  he  made  a  hole  which  he  closed  by  a  piece  of 
thin  membrane  at  b  (Fig.  117),  to  imitate  the  drum  of  the 
natural  ear.  On  the  back  he  fastened  a  tin  plate  which 
served  as  a  support  for  a  little  lever  c  d,  pivoted  to  the  plate 
at  its  middle,  and  resting  at  its  lower  end  c  against  the 
membrane,  and  its  upper  end  d  against  a  strip  of  spring- 
metal  g  which  was  fastened  by  the  two  screws  represented 
to  the  under  edge  of  the  ear.  The  screw  h  was  intended  to 
regulate  the  pressure  of  the  spring  g  on  the  lever  d.  One 


286  THE  AGE  OF  ELECTRICITY. 

wire  from  the  battery  went  to  the  spring  g;  and  the  cur- 


Fig.  118. 


rent  was  conducted,  therefore,  through  that  spring,  through 
the  little  lever  c  d,  then  to  the  tin  supporting  plate,  and 


THE  SPEAKING   TELEPHONE. 


287 


then  to  the  line.  This  is  a  transmitting  instrument  into 
which  speech  is  to  be  uttered.  This  instrument,  in  its 
most  improved  form,  is  represented  in  Fig.  118  ;  and  it  is 
hardly  necessary  to  point  out  how  slight  the  modification 
that  was  effected.  Instead  of  the  carved  ear,  there  is  a 
tube  a,  closed  as  before  with  a  membrane  b.  On  the  tube 
is  a  support  e,  which  carries  a  little  pivoted  lever  c  as 
before,  one  end  resting  against  the  membrane,  the  other 
against  a  spring  d  which  can  be  adjusted  to  the  lever. 
The  current  goes  from  the  battery  to  the  spring,  so  to 


Fig.  119. 

the  lever,  to  the  metal  tube  and  its  support,  and  so  to 
line. 

Reis'  last  form  of  transmitter  is  represented  in  Fig.  119. 
It  is  simply  a  box  A,  into  the  side  of  which  passes  a 
speaking-tube.  In  the  lid  of  the  box  is  a  round  hole,  in 
which  is  arranged  as  before  a  membrane  diaphragm.  On 
this  diaphragm  is  fastened  a  flat  bit  of  platinum,  which 
is  electrically  connected  to  a  binding-post  by  a  strip  of 
copper.  Above  the  platinum  rests  a  point  of  the  same 
metal,  which  was  fastened  at  the  apex  of  a  loose  angular 
piece  of  metal.  The  angle  piece  is  supported  at  the  end  of 


288  THE  AGE   OF  ELECTRICITY. 

one  leg  b  by  a  sort  of  pivot ;  and  at  the  end  of  its  other  leg 
a  it  has  a  point  dipping  into  a  little  cup  of  mercury.  This 
mercury  cup  is  connected  by  a  wire  to  the  binding-screw 
/,  in  the  engraving,  so  that  the  current  from  the  battery 
might  be  said  to  enter  at  the  screw  /,  thence  go  to  the 
little  tripod  or  angle  piece ;  and  as  the  point  at  the  apex 
of  this  rests  by  gravity  simply  on  the  scrap  of  platinum 
fastened  on  the  diaphragm,  the  current  proceeds  to  the 
platinum,  and  so  by  the  copper  strip  to  the  screw  d, 
hence  to  line. 

Reis  made  two  receiving  instruments,  one  of  which  is 
shown  in  Fig.  119  in  connection  with  the  transmitter  just 
described.  It  is  simply  and  purely  Page's  needle,  which 
is  seen  passing  through  two  supports,  surrounded  by  its 
coil,  and  resting  on  a  sounding-box.  Reis'  other  receiver, 
which  he  abandoned  in  favor  of  the  needle  instrument,  is 
represented  in  Fig.  118.  It  was  modified  from  a  telegraph- 
sounder  ;  m  m  being  the  usual  electro-magnets,  before 
which  was  suspended  an  armature  *',  loosely  hung  in  a 
standard  &,  and  provided  with  adjusting  screws  /  and  o. 
The  current  passed  through  the  magnet  coils  in  the  usual 
way. 

The  reader  has  now  before  him  substantially  all  that 
Reis  did.  The  instruments  represented  in  Fig.  119  were 
those  manufactured  for  the  market,  and  they  found  their 
way  to  the  United  States.  They  were  exhibited  in  New 
York  in  1869,  1870,  and  1871. 

But  how  do  these  instruments  work?  And  how,  if  at 
all,  do  they  transmit  speech?  And,  if  they  transmit 
speech,  why  did  the  world  not  have  the  speaking  tele- 
phone twelve  or  fifteen  years  earlier  than  it  did?  It  has 
cost  already  several  hundred  thousand  dollars  just  to  talk 
about  those  questions,  and  the  end  of  the  expense  is  not 
yet  —  in  this  country,  at  least.  However  existing  contro- 


THE  SPEAKING   TELEPHONE.  289 

versies  may  be  decided,  three  irreconcilable  views  of  Reis' 
instruments  will  always  be  taken  ;  and  these  are  :  — 

First,  That  Reis  merely  combined  Bourseul's  contact- 
breaking  disk  and  wire  with  Page's  singing  needle  ;  using 
the  voice  to  make  the  disk  vibrate,  and  so  make  and 
break  the  circuit  correspondingly  with  the  frequency  of 
the  vibrations.  This  doctrine  denies  the  possibility  of 
Reis'  apparatus  ever  having  transmitted  speech,  or  ever 
having  been  able  to  do  so,  because  an  electrical  current  now 
interrupted  and  now  established  must  during  the  periods 
of  interruption  cease  altogether.  Hence  the  necessary 
vibrations  are  constantly  being  dropped  out,  and  can  never 
be  reproduced  at  the  receiver,  because  never  existing  on 
the  line  ;  while  those  .that  do  affect  the  current  simply 
cause  the  needle  to  sing  in  its  own  voice,  depending,  as 
we  have  already  explained,  upon  the  rapidity  or  frequency 
of  the  closing  of  the  circuit. 

Second,  That  Reis'  instruments,  even  if  they  do  make 
and  break  the  circuit  in  the  manner  described,  will  never- 
theless transmit  speech  by  virtue  of  the  making  and  break- 
ing. This  is  absurd ;  and  although  it  has  been  gravely 
advanced,  and  innumerable  specious  contrivances  devised 
to  establish  its  truth,  all  that  these  show  is  that  speech 
can  be  transmitted  through  certain  things  different  from 
Reis'  apparatus  even  despite  occasional  interruptions  in 
the  circuit,  —  just  as  an  occasional  pressure  on  the  wind- 
pipe may  stop  speech  from  time  to  time,  and  yet  the 
speaker  manage  to  make  himself  understood. 

Third,  That  Reis'  contact  points  above  noted  never 
broke  circuit  at  all,  but  were  always  held  together  by  the 
weight  of  the  superimposed  angle  piece  in  Fig.  119,  or 
the  spring  in  Fig.  118.  When  this  is  the  case,  Reis'ttrans- 
mitter  if  carefully  used  will  transmit  spoken  words. 

If   Reis'  transmitter  was  not  capable  of   transmitting 


290  THE  AGE  OF  ELECTRICITY. 

speech,  it  is  of  course  immaterial  whether  his  receiver 
could  reproduce  speech  or  not.  He  never  could  have 
known  whether  it  was  or  was  not  operative  for  the  pur- 
pose. If,  however,  Reis'  transmitter  could  and  did  trans- 
mit speech,  then  it  is  very  important  to  know  whether  his 
receiving  instrument  would  reproduce  speech,  for  a  like 
reason.  It  will  suffice  here  to  say,  that,  with  a  fully 
operative  transmitter,  either  of  Reis'  receivers  can  be 
made  to  reproduce  the  speech  sent. 

At  the  time  that  this  work  is  written  (1886),  a  contest 
of  unexampled  bitterness,  into  which  even  the  Government 
of  the  United  States  has  been  drawn  as  a  party,  rages 
over  the  question  who  invented  the  arc  of  transmitting 
articulate  speech  by  electricity,  and  the  speaking  tele- 
phone. It  is  scarcely  possible  to  make  even  the  simplest 
statements  without  risking  acrimonious  contradiction  from 
some  quarter  or  other :  even  to  doubt,  is  often  to  invite 
instant  condemnation.  In  the  recital  which  follows,  it 
has  been  the  endeavor  to  state  facts,  without  partisan 
color. 

The  multiple  harmonic  telegraph  of  Mr.  Elisha  Gray, 
which  has  already  been  described  in  the  chapter  on  teleg- 
raphy, was  widely  exhibited  throughout  the  United  States 
in  the  years  1875  and  early  in  1876,  under  the  name  of 
the  "  telephone."  During  this  period,  and  for  some  time 
before,  Mr.  Gray  had  been  studying  the  problem  of  articu- 
late transmission.  It  is  alleged,  that,  as  early  as  1874, 
he  invented  an  apparatus  which  is  a  complete  speaking 
telephone  ;  but  it  appears  that  he  did  not  construct  it,  nor 
in  any  wise  test  it,  until  some  years  afterwards.  At  the 
time  Gray  was  lecturing  upon  his  harmonic  telegraph,  — 
or  musical  telephone,  as  it  was  then  commonly  called, 
—  and  prosecuting  his  other  researches,  Mr.  Alexander 
Graham  Bell,  then  a  teacher  of  a  system  of  visible  speech 


THE  SPEAKING   TELEPHONE. 


291 


to  the  deaf  and  dumb  in  a  public  institution  in  Boston, 
was  likewise  at  work  upon  telegraphic  inventions.  Foi 
several  years,  beginning  in  1870,  Mr.  Bell  was  studying 
multiple  telegraphic  transmission  by  musical  tones.  He 
devised  various  forms  of  apparatus  for  that  purpose,  and, 
among  other  things,  a  receiving  instrument  which  is  rep- 
resented in  Fig.  120.  This  consists  simply  of  an  electro- 
magnet placed  vertically,  over  the  poles  of  which  extends 
a  thin  bar  of  steel  clamped  to  a  support.  This  con- 
trivance was  contrived  for  use  with  a  device  for  mechani- 
cally interrupting  the  current,  the  latter  consisting  in  a 
steel  reed  kept  in  continuous  vibration  by  an  electro- 
magnet and  a  local 
battery.  The  reed  in 
vibrating  made  and 
broke  the  current  to 
the  line  ;  and  this  cur- 
rent, passing  to  the 
electro-magnet  in  the 
receiving  apparatus, 
caused  that  magnet  to  attract 
steel  bar  before  it.  If 


Fig.  120. 


and  release  the  elastic 
the  normal  rate  of  vibration  of 
the  transmitting  reed  was  the  same  as  that  of  the  re- 
ceiving reed,  then  the  latter  would  vibrate  strongly,  and 
yield  a  note  of  the  same  pitch  as  that  of  the  transmitting 
reed  ;  but  if  the  normal  rates  of  vibration  of  the  two  reeds 
were  different,  then  the  receiver  would  keep  silent.  The 
principle  of  this  is  fully  explained  on  page  238,  in  refer- 
ence to  Gray's  harmonic  telegraph. 

During  1874  Mr.  Bell  did  a  great  deal  of  thinking  about 
transmitting  speech  by  electricity,  and  a  little  work  on  his 
harmonic  telegraph ;  and  this  state  of  affairs  continued 
until  the  summer  of  1875.  On  the  second  day  of  June 
of  that  year,  wrhile  experimenting  with  his  multiple  tele- 


292  THE  AGE   OF  ELECTRICITY. 

graph  apparatus,  Mr.  Bell  made  an  accidental  discovery 
which,  he  says,  "  convinced  me  in  a  moment  that  the 
speaking  telephone  I  had  devised  in  the  summer  of  1874 
would  if  constructed  prove  a  practically  operative  instru- 
ment." The  Italics  are  ours.  Mr.  Bell  had  arranged  in 
his  workshop  three  experimental  telegraph-stations,  at  one 
of  which  were  several  of  his  circuit-breaking  transmitting 
reeds,  and  at  each  of  the  others  an  equal  number  of  re- 
ceivers, of  the  form  represented  in  Fig.  120.  Thus  there 
were  three  transmitters  tuned  to  notes  of  different  pitch, 
as  A,  B,  and  C,  at  one  station  ;  and  at  each  of  the  other 
stations,  three  receivers  tuned  to  the  same  notes,  A,  B,  C. 
When  transmitter  A  was  in  operation,  only  the  reeds  A 
at  the  two  distant  stations  should  respond ;  and  so,  for 
transmitters  B  and  C,  only  the  reeds  B  and  C  should 
correspondingly  vibrate.  While  the  experiment  was  in 
progress,  Mr.  Bell's  assistant,  Mr.  Watson,  finding  that 
one  of  the  reeds  of  the  receivers  at  the  station  where  he 
was  located  adhered  to  the  pole  of  the  magnet,  forcibly 
plucked  it  away.  At  the  same  moment  Mr.  Bell,  at  the 
other  receiving  station,  noticed  a  motion  in  the  reed  of 
the  receiver,  which  corresponded  to  the  receiver  whose 
reed  had  been  plucked.  "At  all  events,"  he  says,  "the 
reed  of  the  receiver  at  station  2  vibrated  at  a  time  when 
no  vibration  was  expected,  so  that  the  fact  of  its  vibra- 
tion immediately  attracted  my  attention.  I  therefore  kept 
Mr.  Watson  plucking  the  reed  at  station  3  while  I  made 
various  changes  at  stations  1  and  2.  These  changes 
proved  that  the  vibration  I  had  observed  had  indeed  been 
caused  by  the  plucking  of  the  reed  at  station  3,  even  when 
there  was  no  battery  upon  the  circuit  at  the  time.  To 
make  the  matter  perfectly  sure,  we  separated  the  receivers 
B  of  stations  2  and  3,  and  connected  them  upon  a  circuit 
by  themselves,  as  shown  in  Fig.  5  of  my  March  7,  187G, 


THE  SPEAKING   TELEPHONE. 


293 


patent,  but  without  any  battery  in  the  circuit.  [The  figure 
here  referred  to  by  Professor  Bell  is  represented  in  Fig. 
121.  EE  are  the  two  receivers,  each  having  an  electro- 
magnet, in  front  of  the  pole  of  which  is  arranged  a  spring 
armature  or  reed  A.  The  reed  is  fastened  at  one  end  at 
h.~\  Upon  plucking  the  reed  of  one  of  the  receivers,  the 
reed  of  the  other  was  thrown  into  very  considerable  vibra- 
tion. The  vibrations  produced  by  the  plucking  were  still 
more  intense  when  a  battery  was  included  in  the  circuit.  A 
number  of  experiments  were  made  to  prove  that  the  con- 
siderable amplitude  of  movement  noticed  was  not  caused  by 
any  vibrations  mechanically  conducted  along  the  wire  frorj 
one  instrument  to  the  other,  but  that  the  vibration  of  tha 


one  receiving  reed  was  due  to  electrical  undulations  caused 
by  the  vibration  of  the  other  receiving  reed.  The  discovery 
therefore  that  was  made  on  the  2d  of  June,  1875,  teas  that 
the  vibrations  caused  in  the  armature  of  a  receiving  instru- 
ment, by  electrical  undulations  occasioned  by  the  vibration 
of  the  armature  of  another  instrument  in  the  same  circuit 
as  the  first,  would  be  of  very  considerable  force.  As  I  have 
already  explained,  I  had  had  the  idea  since  the  summer 
of  1874,  that  vibrations  produced  in  this  way  would  be  of 
very  slight  amplitude,  and  that  they  might  not  prove  suffi- 
ciently violent  to  produce  audible  effects  that  would  prove 
practically  useful  either  for  the  purpose  of  the  reproduc- 
tion of  articulate  speech,  or  for  the  purposes  of  multiple 
telegraphy.  The  experiments  described  above  convinced 


294  THE  AGE  OF  ELECTRICITY. 

me  that  this  was  a  mistake.  The  vibrations  produced  in 
tuned  reeds  were  so  great  in  amplitude  that  I  felt  sure 
that  they  were  even  sufficiently  great  to  be  mechanically 
utilized  in  any  system  of  multiple  telegraphy.  Even  when 
the  reeds  of  the  two  instruments  connected  in  circuit  (Fig. 
124),  (but  without  a  battery),  were  not  in  tune  with  one 
another,  —  that  is,  did  not  have  the  same  normal  rate  of 
vibration, — the  feeble  forced  vibrations  electrically  pro- 
duced in  the  one  by  the  mechanical  plucking  of  the  other, 
though  barely  sufficient  to  produce  a  visible  motion,  were 
quite  sufficient  to  cause  a  very  perceptible  sound." 

The  reader  has  now  before  him  Mr.  Bell's  own  descrip- 
tion, not  exactly  of  how  he  invented  the  speaking  tele- 
phone, but  how  he  became  convinced  that  a  speaking 
telephone  which  he  had  in  his  mind  would  prove  "  a  prac- 
tically operative  instrument." 

So  far  he  had  simply  observed  that  the  current  produced 
in  the  coil  of  an  electro-magnet,  by  vibrating  an  armature 
in  front  of  the  pole  of  that  electro-magnet,  was  stronger 
than  he  had  believed  ;  that  is,  it  was  strong  enough,  after 
passing  over  a  telegraph-line,  to  set  another  armature,  in 
front  of  another  electro-magnet,  vibrating  audibly. 

Mr.  Bell's  next  step  was  to  try  whether  he  could  move 
the  armature  —  the  reed  —  of  the  sending  instrument  by 
the  air-waves  produced  by  the  voice,  instead  of  mechani- 
cally by  the  finger.  Just  as  Reis  had  done  before  him, 
and  the  inventor  of  the  phon autograph  before  Reis,  he 
made  a  hollow  tube,  and  covered  one  end  with  a  piece  of 
membrane.  He  fastened  his  vibrating  reed  to  the  centre 
of  that  membrane.  The  apparatus  as  Mr.  Bell  says  he 
made  it  is  represented  in  Fig.  122.  The  electro-magnet  is 
placed  above  the  membrane  diaphragm  ;  the  armature  fas- 
tened to  the  centre  of  the  membrane.  In  order  to  leave 
the  armature  free  to  follow  the  membrane,  the  former  was 


THE  SPEAKING   TELEPHONE. 


295 


hinged  to  its  support.  Mr.  Bell  supposed  that  when  some 
one  talked  to  the  diaphragm  of  this  instrument,  the  magnet 
being  connected  to  a  line  of  wire,  another  person  listening 
at  a  similar  instrument  also  connected  to  the  line  would 
hear  what  was  said.  Unfortunately,  when  he  caused  the 
instruments  to  be  made,  they  would  not  operate.  He  says 
he  "  knew  from  theory  that  the  articulation  was  there  ;  " 
but  there  is  obviously  a  wide  difference  between  knowing 
of  the  presence  of  a  thing  by  theory,  and  producing  it. 

This  was  the  condition  of  affairs  when  Professor  Bell 
obtained  his  celebrated 
patent  which  has  since 
been  judicially  con- 
strued to  cover  the 
whole  art  of  transmit- 
ting speech  by  electri- 
city. Like  Reis,  he  had 
formulated  theories  in 
his  own  mind,  and  had 
made  apparatus  which 
he  hoped  would  practi- 
cally realize  them.  But 
neither  Reis  so  far  as  the  world  knew,  nor  Bell  so  far  as 
he  knew,  had  ever  successfully  transmitted  one  word  by 
electricity,  at  the  respective  times  when  death  ended  the 
labors  of  the  one,  and  when  the  monopoly  of  a  great 
public  need  fell  into  the  hands  of  the  other. 

By  the  summer  of  1876  Mr.  Bell  had  considerably 
modified  the  form  of  his  apparatus  ;  and  at  the  Centennial 
Exposition  he  exhibited  it  before  various  distinguished 
persons,  and  succeeded  in  transmitting  a  few  simple  and 
easily  recognizable  words  and  phrases. 

During  the  following  year  Mr.  Bell  applied  himself 
assiduously  to  the  improvement  of  his  apparatus,  and 


Fig.  122. 


296 


THE  AGE  OF  ELECTRICITY. 


finally  by  June,  1877,  brought  it  to  the  familiar  form  in 
which  it  has  remained  ever  since.  Our  engraving  (Fig. 
123)  shows  it  split  in  two  lengthwise.  The  outer  casing  is 
of  hard  rubber.  Through  the  middle  runs  a  bar  magnet, 
on  the  end  of  which  is  the  wire  coil.  The  ends  of  the  coil 


Fig.  123. 

are  connected  by  wires  running  through  the  case  to  two 
binding-posts,  to  which  the  circuit  connections  are  fas- 
tened. Between  the  cover  and  case  proper  is  clamped  the 
diaphragm  of  thin  sheet-iron  which  is  disposed  as  close  to 
the  end  of  the  magnet  as  possible  without  touching  it. 


fig.  124. 

Finally,  in  the  cover  there  is  a  recess  which  serves  to  con- 
verge the  sounds  uttered  into  the  instrument  toward  the 
central  sound  aperture.  This  is  known  as  a  magneto 
telephone,  and  may  be  used  both  as  a  transmitter  and 
a  receiver,  —  that  is,  it  may  be  employed  at  both  ends  of  a 
line  as  shown  in  Fig.  124,  which  is  simply  a  diagram  of  the 


THE  SPEAKING    TELEPHONE.  297 

important  parts  ;  A  and  B  being  two  permanent  magnets, 
C  and  D  being  diaphragms  respectively  in  front  of  each, 
and  E  and  F  being  the  coils.  One  end  of  each  coil  may 
be  connected  to  ground,  and  the  other  ends  connected  to 
line.  When  permanent  magnets  are  used,  the  transmitting 
instrument  produces  its  own  current :  when  a  battery  is 
placed  in  circuit,  the  telephone  current  is,  as  already 
stated,  superposed  on  the  main  current.  The  first  tel- 
ephone lines  commercially  employed  had  magneto  tele- 
phones for  both  transmitters  and  receivers,  but  at  the 
present  time  in  this  country  the  magneto  telephone  is  used 
solely  as  a  receiver. 

It  is  a  matter  of  history,  that  Mr.  Bell  has  been  the 
recipient  of  great  honors,  not  merely  as  the  inventor  of 
the  electric  speaking  telephone,  but  of  the  art  of  teleph- 
ony, —  of  transmitting  and  receiving  articulate  speech 
by  the  aid  of  the  electrical  current.  And  it  is  also  well 
known,  that,  under  Mr.  Bell's  earliest  patent  bearing  date 
March  7,  1876,  a  gigantic  corporation  has  asserted  an  in- 
flexible control  in  the  United  States  over  every  telephone 
line.  This  control  mainly  is  based  on  the  famous  fifth 
claim  of  Mr.  Bell's  patent,  which  is  as  follows  :  — 

"The  method  and  apparatus  for  transmitting  vocal  or 
other  sounds  telegraphically,  as  herein  described,  by  caus- 
ing electrical  undulations  similar  in  form  to  the  vibrations 
of  the  air  accompanying  the  said  vocal  or  other  sounds, 
substantially  as  set  forth." 

We  have  already  alluded  incidentally  to  the  undulatory 
current  in  contradistinction  to  the  intermittent  or  inter- 
rupted current.  The  so-called  undulatory-current  theory 
is  that  which  is  most  commonly  accepted  to  explain  the 
action  of  the  telephone.  It  involves  the  idea  that  only 
an  unbroken  current,  variable  in  strength,  can  be  modified 
by  all  the  characteristics  of  a  sound-wave ;  that  such  a 


298 


THE  AGE  OF  ELECTRICITY. 


current  will  be  undulatory  in  form,  and  that  its  undula- 
tions will  copy  or  correspond  to  all  the  undulations  of  the 
sound-waves  affecting  the  transmitting  telephone,  however 
minute,  and,  after  passing  over  a  wire,  will  cause  in  the 
receiving  instrument  the  reproduction  of  the  original 
sounds  in  all  their  characteristics.  This  is  substantially 
the  undulatory-current  theory. 

There  are  two  principal  ways  in  which  an  electric  cur- 
rent is  subjected  to  the  influence  of  the  voice.  One,  we 
have  already  seen,  involves  an  armature  in  the  form  of  a 
thin  plate,  which  is  vibrated  by  the  sound-waves  due  to 


Fig.  125. 


speech  in  front  of  the  pole  of  an  electro-magnet,  as  rep- 
resented in  Fig.  124.  The  other  method  depends  simply 
on  interposing  in  a  closed  circuit,  two  pieces  of  conducting 
material  in  loose  but  constant  contact  as  represented  in 
Fig.  125.  One  of  these  pieces,  A,  may  be  attached  to  the 
plate  vibrated  by  the  speaker's  voice,  and  the  other  piece, 
B,  may  be  held  in  constant  contact  with  the  first  by  a 
spring,  for  example.  The  battery  current  passes  from 
one  piece  to  the  other,  then  to  the  line,  and  to  a  magneto 
receiving  instrument.  When  speech  is  uttered  before  the 
diaphragm,  the  vibrations  of  the  plate  communicate  them- 
selves to  the  loose  joint,  and  create  variations  in  the  re- 
sistance offered  by  this  joint  to  the  current.  The  result 


THE  SPEAKING   TELEPHONE.  299 

is,  that  the  current  is  modified  by  the  diaphragm  vibrations, 
just  as  it  is  when  the  diaphragm  is  moved  before  the  pole 
of  a  magnet ;  only,  in  the  one  case  a  current  already  flow- 
ing is  more  or  less  diminished  in  strength,  and  in  the  other 
it  is  more  or  less  increased  in  strength.  To  illustrate  : 
Suppose  there  is  attached  to  a  bucket  of  water  a  flexible 
pipe,  as  in  Fig.  126,  through  which  the  water  can  freely 
flow.  Then,  by  compressing  the  pipe  in  the  hand,  the 
escape  of  the  water  can  be  more  or  less  prevented,  while 
some  flow  always  continues.  The  contact  pieces  -4,  /?, 
in  Fig.  125,  when  governed  by  the  diaphragm,  act  like  the 
hand  in  Fig.  126.  Again,  suppose  the  case  of  a  railway- 
train,  which  can  be  made  to  move  faster  while  constantly 


Fig.  126. 

running,  by  turning  on  more  or  less  steam  to  the  engine : 
that  represents  the  conditions  of  the  magneto  telephone. 
So  also,  while  running  at  a  given  speed,  the  train  can  be 
more  or  less  checked  by  the  brakes  ;  that  represents  the 
conditions  of  the  resistance  telephone.  In  both  cases,  the 
train  keeps  on  moving,  but  its  speed  is  varied. 

The  reader  will  doubtless  notice  at  once  the  similarity 
between  the  resistance  form  of  telephone  represented  in 
Fig.  125,  and  Reis'  transmitter  represented  in  Fig.  118. 
The  whole  controversy  as  to  Reis  hinges  simply  on  the 
question  whether  Reis  did  or  did  not  maintain  his  loose 
contact  pieces  in  constant  contact.  If  he  did,  he  had  a 
resistance  telephone,  using  an  unbroken  current,  which 
will  transmit  speech :  if  he  did  not,  he  had  simply  a , 


300  THE  AGE   OF  ELECTRICITY. 

circuit-breaker,  causing  a  broken  current,  which  will  not 
transmit  speech. 

Leaving  the  Reis  question  aside,  however,  it  is  a  singu- 
lar fact,  that  the  first  articulate  speech  obtained  by  Mr. 
Bell  was  transmitted  not  only  after  his  patent  had  been 
obtained,  but  with  an  apparatus  which  Mr.  Bell  had  never 
before  made,  or  even  described  so  that  any  one  else  could 
make  it.  In  fact,  the  first  words  sent  by  Mr.  Bell  were 
not  transmitted  by  the  magneto  telephone  at  all,  but  by  a 
very  imperfect  form  of  resistance  instrument,  the  con- 
struction of  which  was  first  described,  not  by  Mr.  Bell, 
but  by  Mr.  Elisha  Gray.  It  consisted  of  a  membrane 
vibrated  by  the  voice,  and  carrying  a  wire  which  dipped 
in  water.  A  battery  current  was  conducted  to  the  water, 
passed  to  the  wire,  and  so  to  the  line.  When  the  mem- 
brane was  vibrated,  it  moved  the  wire  up  and  down  in  the 
water,  and  so  altered  the  length  of  the  non-submerged 
portion  of  the  wire,  thus  varying  its  resistance  to  the 
passage  of  the  current.  For  practical  purposes  this  ap- 
paratus is  of  no  value,  but  it  will  always  be  of  great 
historical  interest  for  the  reasons  above  stated. 

In  May,  1878,  Professor  D.  A.  Hughes  announced  his 
discovery  of  the  microphone,  so  called  because  it  rendered 
audible  very  minute  sounds  ;  and  this  discovery  was,  that, 
if  two  pieces  of  conducting  material  be  supported  in  very 
delicate  contact,  then  the  resistance  offered  by  the  joint 
to  a  current  passing  through  it  will  be  modified  by  very 
faint  sounds,  and  the  current,  correspondingly  affected, 
caused  to  reproduce  them  in  a  receiving  telephone.  This 
is  of  course  the  principle  of  the  resistance  telephone, 
which,  in  fact,  is  now  commonly  known  as  the  microphone. 
Hughes  made  his  microphone  in  the  form  represented  in 
Fig.  128,  in  which  A  is  a  stick  of  hard  carbon  pointed  at 
its  ends,  and  held  between  two  supports  of  like  material 


THE  SPEAKING   TELEPHONE. 


301 


projecting  from  an  upright  board.  The  battery  current 
was  led,  as  indicated  by  the  wires,  to  one  support  through 
the  carbon,  and  out  through  the  other  support ;  and  a  re- 
ceiving telephone  was  connected  in  the  circuit.  A  great 
many  stories  about  hearing  flies'  footsteps,  etc.,  were 
published  when  this  apparatus  first  appeared,  which  were 
more  fantastic  than  accurate.  It  is  true  that  some  faint 
sounds  can  at  times  be  recognized  ;  but  as  a  general  rule, 
true  of  all  over-delicate  microphonic  contacts,  the  breaks 


Fig.  127. 

in  continuity  of  the  circuit  caused  by  vibrations  being 
strong  enough  to  actually  separate  the  parts  of  the  loose 
joint,  result  simply  in  explosive  cracks  and  snaps  in  the 
receiver,  which  practically  obliterate  all  other  sounds.  In 
the  resistance  telephone,  —  the  transmitter  of  the  present 
day,  —  the  chief  problem  has  always  been  the  devising  of 
mechanical  means  of  holding  the  contact  pieces  together 
so  delicately  that  they  will  be  under  control  of  the  minut- 
est speech  vibrations,  and  yet  not  so  lightly  that  the 
grosser  vibrations  —  as  when  words  are  loudly  spoken  — 
can  throw  them  apart. 


302  THE  AGE   OF  ELECTRICITY. 

Shortly  after  the  announcement  by  Hughes  of  his 
microphone,  Mr.  T.  A.  Edison  laid  claim  to  the  discov- 
ery, asserting  that  he  had  some  time  prior  found  out  that 
"semi-conductors" — whatever  they  may  be,  including 
carbon,  however  —  vary  their  resistance  with  pressure. 
Mr.  Edison  at  various  times  has  contrived  telephones  in 
which  a  block  of  carbon,  for  example,  is  pressed  against 
a  diaphragm.  It  has  been  conclusively  demonstrated  by 
many  investigators,  that  the  pressure,  greater  or  less,  on 
carbon,  has  nothing  to  do  with  variations  of  resistance 
offered  by  that  material  to  a  current.  Mr.  Edison's 
instruments  for  a  short  time  were  commercially  used  in 
this  country. 

Of  the  various  claimants  to  the  invention  of  the  tele- 
phone, none  has  presented  a  more  remarkable  history 
than  Daniel  Drawbaugh.  Mr.  Drawbaugh  is  one  of 
those  universal  geniuses  capable  of  turning  his  hand  to 
any  mechanical  work,  and  of  doing  it  well.  He  has 
always  resided  in  an  out-of-the-way  little  hamlet  called 
Eberly's  Mills,  near  Harrisburg,  Penn.  As  an  electri- 
cian, he  is  self  taught.  Between  the  years  18G7  and 
1876,  he  claims  to  have  invented  and  actually  used 
every  type  of  telephone  now  known.  He  began  with  a 
transmitter  made  out  of  a  jelly- tumbler,  in  which  he  used 
powdered  carbon  to  vary  the  resistance  correspondingly 
to  the  motion  of  a  diaphragm  vibrated  by  the  voice ;  and 
a  receiver  contrived  from  a  mustard-can,  but  in  other 
respects  nearly  identical  with  the  first  telephones  made 
by  Professor  Bell.  From  these  devices  as  starting-points, 
onward,  he  has  constructed  a  series  of  telephones,  more 
and  more  specialized  in  construction,  until  finally  the 
instruments  which  he  claims  to  have  had  at  the  time 
when  Professor  Bell  made  his  earliest  experiments  ap- 
proach closely  in  efficiency  to  the  best  forms  of  the  pres- 


THE  SPEAKING   TELEPHONE.  303 

ent  day.  Mr.  Drawbaugh  has  produced  a  large  number 
of  his  telephones,  and  many  witnesses  to  prove  that  he 
had  them  at  the  times  he  fixes.  His  claims  are  at  this 
writing  before  the  courts  for  adjudication.  If  they  are 
ultimately  sustained,  there  can  be  no  question  but  that 
Mr.  Drawbaugh's  position  as  an  electrical  discoverer  will 
be  wholly  unrivalled.  Within  the  last  four  years,  he  has 
invented  over  thirty  new  telephones. 

At  the  date  of  this  work  (1886) ,  over  a  thousand  patents 
in  the  United  States  alone  have  been  granted  for  various 
forms  of  telephones,  and  devices  thereunto  appertaining. 
The  great  majority  of  instruments  differ  merely  in  unes- 
sential details.  With  the  resistance  transmitters,  changes 
on  means  for  holding  the  two  contact  pieces  together  have 
been  rung  to  such  an  extent  that  it  seems  that  every  con- 
ceivable contrivance  for  the  purpose  must  have  been  sug- 
gested. Magneto  telephones  are  not  used  commercially 
as  transmitters  ;  for  the  modifications  they  produce  in  the 
current  are  feeble  compared  with  those  caused  by  the 
resistance  instrument.  They  are,  however,  commonly 
employed  as  receivers ;  and,  as  has  been  already  stated, 
the  form  which  they  now  have  has  undergone  no  material 
change  for  some  nine  years.  An  immense  amount  of 
ingenuity  has  also  been  expended  in  devising  telephone 
circuits  and  systems  so  as  to  allow  of  intercommunication 
between  exchanges  and  subscribers. 

The  form  of  transmitting  telephone  in  common  use 
throughout  the  United  States  is  that  known  as  the  Blake 
transmitter,  a  sectional  view  of  which  is  given  in  Fig. 
128.  The  contact  pieces  are  here  a  platinum  point  which 
is  supported  on  a  light  spring  c,  and  a  button  of  carbon, 
7i,  held  in  a  heavy  mass  or  anvil  e,  which  is  supported  by 
a  spring  d.  Both  springs  c  and  d  are  held  in  a  plate  F, 
which  is  itself  sustained  by  a  spring  plate  g  upon  a  bracket 


304 


THE  AGE   OF  ELECTRICITY. 


B'.  The  platinum  point  rests  against  the  diaphragm,  and 
also  against  the  carbon  button  ;  these  parts  being  held  in 
light  contact  by  the  several  springs.  On  the  lower  part 
of  the  plate  F  is  an  inclined  plane  against  which  bears 
the  point  of  an  adjusting-screw  G.  The  current  from  the 

battery  is  conducted 
through  the  primary  wire 
of  the  induction  coil  /, 
thence  through  the  con- 
tact pieces,  and  so  back 
to  battery.  The  second- 
ary wire  of  the  induction 
coil  communicates  with 
the  line.  The  Blake 
transmitter  is  by  no 
means  the  best,  or  even 
one  of  the  best,  of  the 
carbon  transmitters. 

Various  forms  of  trans- 
mitters have  been  devised, 
in  which  springs  for  hold- 
ing the  carbon  contact 
pieces  together  are  omit- 
ted, and  the  action  of 
gravity  substituted.  One 
of  the  simplest  instru- 
ments of  this  kind  was 
devised  by  Mr.  Daniel 
Drawbaugh  in  1881,  and 
is  illustrated  in  Fig.  129.  To  the  rear  side  of  a  diaphragm 
A  is  attached  a  little  prism  B  of  hard  carbon  ;  and  a  simi- 
lar prism  C  is  secured  to  the  back-board  of  the  instrument. 
These  prisms  do  not  touch  each  other,  but  resting  upon 
their  inclined  faces  is  a  cylinder  />,  also  of  carbon.  The 


Fig.  128. 


THE  SPEAKING    TELEPHONE. 


305 


battery  current  passes  through  the  three  pieces  of  carbon, 
which  remain  always  in  proper  adjustment  simply  by  the 
weight  of  the  carbon  cylinder.  This  instrument  has  been 
adopted  by  the  United  States  Signal  Service,  and  has  been 
officially  pronounced  of  special  efficiency 
for  military  purposes  in  the  field,  etc. 

For  producing  loud  sounds  in  the  re- 
ceiving instrument,  the  transmitters  which 
use  blocks  or  buttons  of  carbon  are  far 
inferior  to  those  employing  carbon  in 
comminuted  form.  The  usual  construc- 
tion of  these  instruments  is  represented 
in  Fig.  130,  in  which  A  is  a  diaphragm 
of  metal,  B  a  fixed  plate  of  metal,  and 
C  a  mass  of  pulverized  coke  placed 
between  the  two.  The  current  passes 
from  the  diaphragm  through  the  coke,  to  the  back  plate, 
and  so  out.  This  telephone  operates  by  reason  of  the 
immense  number  of  contacts  occurring  between 
the  particles  of  carbon.  It  is  necessary  simply 
to  cause  the  air-vibrations  due  to  the  voice  to  jar 
or  shake  the  mass.  Fig.  131  represents  a  pulver- 
ized-carbon  transmitter  constructed  by  the  author, 
in  its  full  working  size.  It  consists  simply  of  a 
cylindrical  box  of  hard  rubber,  lined  within  with 
a  ring  of  brass,  A,  to 
which  one  of  the  con- 
ducting wires  is  fast- 
ened. A  disk  of  brass 


fig.  129. 


Fig,  130. 


Fig.  131. 


B  is  firmly  attached  to 
one  of  the  inner  faces,  so  as  not  to  touch  the  ring  A.  The 
space  in  the  box  is  loosely  filled  with  comminuted  coke, 
and  then  the  cover  is  permanently  fastened  in  place.  In 
external  appearance  the  instrument  is  nothing  but  a  button 


306  THE  AGE  OF  ELECTRICITY. 

from  which  the  connecting  wires  extend.  This  contrivance 
transmits  speech  clearly  when  held  in  the  fingers  close 
to  the  mouth.  Just  why  conducting  bodies  in  loose  but 
constant  contact  will  cause  a  variation  in  the  resistance 
to,  and  so  render  an  electrical  current  capable  of  copying, 
speech  vibrations,  is  not  definitely  known.  Any  pieces 
of  conducting  material  will  so  operate,  —  even  silver,  the 
best  of  electrical  conductors.  The  results,  however,  are 
much  better  when  the  contact  pieces  are  of  carbon,  or 
other  material  of  comparatively  low  conductivity.  It  ap- 
pears probable  that  the  true  cause  of  the  effect  is  varia- 
tions in  the  iufinitesimally  thin  air  film  existing  between 
the  parts  of  the  joint. 

With  all  telephone  transmitters,  at  the  present  time, 
induction  coils  are  used  ;  the  contact  pieces  and  battery 
being  connected  in  the  primary  circuit,  and  the  secondary 
wire  of  the  coil  to  line.  The  principal  object  is  to  increase 
the  electro-motive  force  of  the  modified  current  so  that  it 
may  overcome  the  resistance  due  to  long  lines,  and  thus 
enable  speech  to  be  transmitted  over  greater  distances 
than  if  the  direct  battery  current  were  used. 

As  we  have  stated,  the  ingenuity  of  telephone  inventors 
has  chiefly  been  directed  to  the  production  of  new  forms 
of  transmitters  ;  and  some  of  these  are  remarkable  as  sci- 
entific curiosities.  Professor  Blake  has  transmitted  speech 
by  the  earth's  magnetism,  by  arranging  a  diaphragm  before 
a  rod  of  soft  iron,  the  latter  being  held  in  the  position  of 
the  dipping  needle,  and  thus  becoming  a  magnet  by  induc- 
tion from  the  earth.  Mr.  Bell  has  devised  a  telephone  in 
which  the  vibrations  of  the  diaphragm  produce  a  rubbing 
contact  between  pieces  of  glass  and  silk,  so  that,  as  he 
claims,  the  instrument  "maybe  made  to  transmit  artic- 
ulate speech  by  means  of  frictional  electricity  generated 
by  the  voice  itself."  Another  curious  transmitter  devised 


THE  SPEAKING    TELEPHONE.  307 

by  Mr.  Bell  consists  of  a  toy  balloon  about  six  inches  in 
diameter,  made  of  thin  rubber  and  coated  with  plumbago. 
This  is  held  between  two  fixed  plates,  and  the  current 
passes  over  the  conducting  envelope.  The  expansion  and 
contraction  of  the  body  of  confined  air  in  the  balloon  is 
said  to  modify  the  resistance  of  the  plumbago  coating. 
Neither  of  the  above  instruments  is  of  much  practical 
utility. 

The  great  majority  of  telephone  transmitters  vary  sim- 
ply in  the  arrangement  of  their  contact  pieces.  In  some, 
multiple  contacts  are  used,  ranging  from  two  or  more 
pairs  of  carbons  held  together  by  springs,  and  all  gov- 
erned by  the  same  diaphragm,  up  to  a  dozen  or  more 
pairs.  The  carbons  in  some  instruments  are  held  together 
by  gravity,  and  in  others  by  hydraulic  pressure.  In  some 
forms  of  apparatus,  the  carbon  is  pulverized  :  in  others  it 
takes  the  shape  of  balls  like  shot. 

In  telephone  receivers,  but  little  change  has  been 
effected  since  they  have  come  into  public  use.  In  lieu  of 
one  magnet,  several  are  sometimes  employed.  The  metal 
diaphragm  which  forms  the  armature  is  in  many  forms 
polarized  by  a  metallic  connection  with  the  magnet.  The 
only  part  in  the  telephone  receiver  absolutely  necessary  to 
the  reproduction  of  the  sound  is  the  coil.  The  diaphragm 
may  be  omitted,  and  sound  will  be  heard  from  both  coil 
and  magnet.  If  the  magnet  is  left  out,  the  coil  alone  will 
speak,  though  the  sound  in  such  case  will  be  much  weaker. 
A  simple  platinum  wire  .001  inch  in  diameter  and  six 
inches  long,  stretched  between  a  pillar  and  a  diaphragm, 
will  expand  and  contract  under  the  influence  of  the  cur- 
rent, and  so  reproduce  speech. 

Mr.  Edison  has  invented  .a  so-called  electro-chemical 
telephone-receiver,  in  which  there  is  a  cylinder  composed 
mainly  of  chalk,  against  which  rests  a  platinum  strip 


308 


THE  AGE  OF  ELECTRICITY. 


which  is  also  secured  to  a  diaphragm.  The  circuit  passes 
through  cylinder  and  strip,  and  the  cylinder  is  rotated  at 
uniform  speed.  The  friction  between  cylinder  and  strip 
causes  the  diaphragm  to  be  drawn  inward,  —  that  is,  to- 
ward the  cylinder,  —  so  that  the  diaphragm  is  thus  brought 
to  a  certain  position.  When  a  current  passes  through  the 
instrument,  the  friction  of  strip  and  cylinder  is  reduced, 
and  the  diaphragm  flies  back  by  its  own  elasticity.  As 
the  variation  in  friction  corresponds  to  the  variations  in 
the  strength  of  the  current  coming  to  the  instrument,  the 

diaphragm  is  thus  caused  to 
vibrate  so  as  to  reproduce 
speech  sent  from  the  other 
end  of  a  line.  This  appara- 
tus produces  loud  sounds,  but 
has  not  come  into  any  practi- 
cal use. 

One  of  the  most  ingenious 
of  the  telephones  is  Professor 
Dolbear's  condenser  receiver, 
which  is  represented  in  Fig. 
132.  This  consists  simply  of 
two  metallic  disks  (7,  Z),  sup- 
ported in  the  case  of  the  instrument  so  as  to  be  very  close 
together,  but  not  in  contact.  One  disk  is  pressed  upon 
by  a  screw  at  its  middle,  and  is  thus  prevented  from 
vibrating ;  the  other  is  free  to  vibrate.  One  of  these 
disks  is  connected  to  line,  the  other  to  earth.  The  line 
wire  at  the  transmitting  end  is  connected  to  the  secondary 
wire  of  an  induction  coil,  in  the  primary  circuit  of  which  a 
transmitter  is  included.  As  the  varying  currents  flow  into 
and  out  of  this  condenser,  the  two  disks  attract  one  another 
more  or  less  strongly ;  and  thereby  vibrations  are  set  up 
which  correspond  to  the  vibrations  of  the  original  sounds. 


Fig.  132. 


THE  SPEAKING  TELEPHONE.       309 

There  is  no  instrument  which  employs  such  delicate 
forces,  performs  such  intricate  motions,  or  requires  greater 
accuracy  in  construction,  than  the  telephone.  The  total 
path  of  the  vibrating  air-particle  is  perhaps  one  millionth  of 
an  inch ;  its  period  (half  vibration)  is  as  short  as  ¥  JT  of  a 
second  in  many  instances.  Within  this  small  limit  of  time 
and  space,  lie  packed  all  the  variations  which  distinguish 
from  each  other  all  words  of  all  languages.  The  minute- 
ness of  these  distinctions  escapes  computation  and  state- 
ment ;  and  yet  the  telephone  acts  by  taking  note  of  them 
and  reproducing  them.  The  electrical  force  available  in 
the  magneto  instruments  has  been  reckoned  at  x^oVu^  °f 
that  due  to  a  single  cell  of  battery ;  and  it  is  variations 
of  more  or  less  within  this  maximum  limit  which  give  rise 
to  the  speech  heard  at  the  receiver. 

It  has  been  estimated  that  currents  of  a  ten-millionth 
of  an  ampere  will  give  audible  sounds.  With  delicately 
adjusted  transmitters,  especially  those  using  pulverized 
carbon,  it  is  not  at  all  necessary  to  place  the  instrument 
near  the  mouth  in  speaking.  It  may  simply  be  placed 
against  some  part  of  the  body,  preferably  near  the  chest. 
With  the  little  button  transmitter  above  described,  speech 
can  be  transmitted  clearly  when  the  instrument  is  pressed 
against  the  head,  the  throat,  and  the  chest.  The  best 
results  are  obtained  when  the  apparatus  is  placed  directly 
over  the  breast- bone. 

Wherever  a  conductor  carrying  a  current  is  in  proximity 
to  another  conductor  forming  a  closed  circuit,  the  current 
in  the  first  conductor  induces  a  current  moving  in  opposite 
direction  in  the  second  conductor.  These  induced  cur- 
rents are  often  produced  upon  telephone  lines  by  telegraph 
currents  in  neighboring  wires,  or  stray  currents  in  the  air 
or  earth  ;  and  the  result  is  that  the  telephone  current  may 
be  so  retarded  or  modified  that  it  no  longer  represents 


310  THE  AGE   OF  ELECTRICITY. 

the  speech  vibrations  imposed  upon  it.  A  great  many 
devices  have  been  suggested  to  get  rid  of  this  induction. 
A  return  metallic  conductor  —  double  wire  —  has  been 
found  the  most  efficacious  so  long  as  the  insulation  is 
good ;  but  the  expense  of  two  wires  on  each  circuit  ren- 
ders this  plan  impracticable  for  ordinary  uses.  Cables 
have  been  suggested,  provided  with  envelopes  of  metal 
connected  to  earth  for  the  purpose  of  leading  to  ground 
the  currents  induced  on  them ;  but  these  contrivances 
generally  act  just  the  opposite  from  that  which  is  expected 
of  them,  the  ground  connection  apparently  leading  currents 
from  earth  to  the  line  instead  of  the  reverse  direction. 
"Wherever  a  telephone-line  approximates  a  telegraph-line, 
the  Morse  signals  can  be  plainly  heard  in  the  telephone 
receiver ;  and  where  a  Wheatstone  automatic  instrument 
is  at  work,  or,  as  in  the  case  of  electric-lighting  wires, 
where  a  dynamo  is  supplying  the  current,  the  roars  and 
whirs  heard  in  the  telephone  completely  obliterate  all 
other  sounds. 

The  distance  over  which  a  telephone-line  will  receive 
induced  currents  from  another  -conductor  is  astonishing. 
In  the  early  days  of  the  telephone,  Professor  Blake,  by 
connecting  a  receiver  to  a  railroad- track,  heard  distinctly 
the  Morse  signals  traversing  the  wires  on  the  poles  more 
than  forty  feet  distant. 

Telephoning  over  submarine  cables  is  impracticable  for 
long  distances,  owing  to  the  effects  of  induction  and  retar- 
dation. Tests  on  artificial  lines  representing  the  Atlantic 
cable  show  that  probably  the  maximum  distance  over 
which  speech  can  be  distinguished  does  not  exceed  a  hun- 
dred and  fifty  miles.  Conversation  has,  however,  been 
successfully  maintained  between  Brussels,  Belgium,  and 
Dover,  England,  through  sixty  miles  of  cable  and  two 
hundred  miles  of  air  line.  So  also  speech  has  been  trans- 


THE  SPEAKING   TELEPHONE.  311 

mitted  between  Holyhead  find  Dublin.  In  every  sub- 
marine cable,  before  a  signal  can  be  made  at  the  receiving 
end,  the  whole  cable  must  be  charged  up  with  electricity ; 
and  if  there  be  not  sufficient  electricity  sent  in  for  this 
purpose,  practically  no  signal  appears  at  the  distant  end. 
With  telephone  currents  on  long  cables,  the  whole  of  the 
electricity  is,  as  it  were,  swallowed  up ;  that  is,  none  ap- 
pears at  the  distant  end,  or,  if  it  does  appear,  it  is  rolled 
up  in  one  continuous  wave,  bereft  of  those  rapid  variations 
that  reproduce  sonorous  vibrations. 

A  telephone  circuit  when  in  connection  with  the  earth 
gives  distinct  evidence  of  every  visible  flash  of  lightning, 
however  far  off  the  thunder-storm  may  be.  No  difference 
in  time  has  been  observed  between  seeing  the  flash  and 
hearing  the  sound.  If  the  instrument  be  connected  to  the 
gas  and  water  systems  of  a  house,  distinct  evidence  of 
the  flash  can  be  heard,  and  even  cracklings  attributed  to 
an  aurora  have  been  distinguished  in  this  way.  Earth- 
currents —  those  which  naturally  flow  in  the  earth's  crust 
—  can  often  be  clearly  recognized. 

Professor  Bell  has  proposed  to  utilize  the  inductive  in- 
fluence of  one  circuit  upon  another  to  enable  vessels  at 
sea  to  communicate  by  telephone  without  the  need  of  in- 
tervening wires.  A  conducting  wire,  say,  a  mile  in  length, 
is  trailed  over  the  stern  of  a  vessel,  and  supplied  with 
electricity  from  a  dynamo  on  board.  Circuit  is  made  from 
the  dynamo  through  the  wire,  and  so  back  by  the  water. 
It  is  supposed  that  a  conductor  thus  arranged  will  induce 
currents  upon  a  similar  conductor  trailing  behind  the  other 
vessel,  whenever  the  two  come  in  inductive  proximity,  so 
that  speech  can  thus  be  transmitted.  It  is  not  at  all 
improbable  that  ultimately,  through  the  telephone,  means 
will  be  found  of  warning  vessels  of  the  approach  of  other 
ships,  and  the  direction  in  which  they  are  moving ;  and 


312  THE  AGE  OF  ELECTRICITY. 

possibly,  by  some  thermo-electric  arrangement,  the  prox- 
imity of  icebergs  will  also  be  indicated. 

Theoretically  it  is  difficult  to  assign  any  distance  over 
which  speech  may  not  be  telephonically  transmitted.  Con- 
versation has  easily  been  maintained  through  an  artificial 
resistance  equal  to  that  of  a  telegraph-line  girdling  the 
world ;  but  between  talking  through  artificial  resistances, 
and  actual  wires,  there  is  a  very  great  difference.  So  long 
as  the  effects  of  induction  and  leakage  cannot  be  neutral- 
ized, the  possible  distance  of  telephoning  must  depend  on 
accidental  conditions.  Sometimes  it  is  utterly  impossible 
to  get  speech  over  a  line  a  few  miles  in  length.  Cases 
have  been  found  where  a  line  first  passing  over  water  and 
then  over  earth,  or  extending  over  rock  and  then  gravel, 
would  refuse  to  transmit  until  taken  down  and  carried 
around  the  shore  of  the  water-course  or  away  from  the 
varying  soil.  Speech  has,  however,  been  excellently  trans- 
mitted between  Chicago  and  New  York,  Washington  and 
New  York,  and  Boston  and  New  York,  on  the  regular 
telegraph-lines. 

Telephoning  without  wires  is  already  a  possibility,  and 
promises  extraordinary  results  in  the  near  future.  Tele- 
phones have  been  fixed  upon  a  wire  passing  from  the 
ground  floor  to  the  top  floor  of  a  large  building,  the  gas- 
pipes  being  used  as  a  return,  and  the  Morse  signals  sent 
from  a  telegraph-office  two  hundred  and  fifty  yards  away 
have  been  distinctly  read ;  in  fact,  if  the  gas  and  water 
systems  be  used,  it  is  impossible  to  exclude  telegraphic 
signals  from  the  telephone  circuit.  There  are  several  cases 
on  record  of  telephone  circuits  miles  away  from  any  tele- 
graphic wires,  but  in  a  line  with  the  earth  terminals,  pick- 
ing up  telegraphic  signals.  When  an  electric-light  system 
uses  the  earth,  it-4s  stoppage  to  all  telephonic  communica- 
tion in  its  neighborhood.  The  whole  telephonic  communi- 


THE  SPEAKING   TELEPHONE.  313 

cation  of  Manchester,  England,  was  one  day  broken  down 
from  this  cause  ;  and  in  the  city  of  London  the  effect  was 
at  one  time  so  strong  as  not  only  to  destroy  telephonic 
communication,  but  to  ring  the  bells.  A  telephone  circuit 
using  the  earth  for  return  acts  as  a  switch  to  the  earth, 
picking  up  the  currents  that  are  passing,  in  proportion  to 
the  relative  resistances  of  the  earth  and  the  wire.  Speech 
has  been  transmitted  across  water-courses,  by  the  aid  of 
large  metal  plates  wholly  submerged  ;  the  water  apparently 
closing  the  circuit  between  the  plates. 

Mr.  Van  Rysselberghe,  a  Belgian  electrician,  has  suc- 
ceeded in  transmitting  telegraphic  and  telephonic  messages 
over  the  same  wire  ;  an  apparently  impossible  feat  in  view 
of  the  constant  breaking  of  the  circuit  by  the  telegraph 
instruments,  tending  not  only  to  render  the  current  inter- 
mittent, and  thus  unable  to  receive  all  the  sound- vibrations, 
but  also  to  produce  in  the  receiving  instrument  loud  ex- 
plosive noises  which  effectually  drown  articulation.  Mr. 
Van  Rysselberghe  has  succeeded  in  talking  between  Paris 
and  Brussels,  over  a  wire  nearly  two  hundred  miles  long, 
which  was  used  at  the  same  time  for  ordinary  telegraph- 
ing. His  principle  is  to  retard  the  telegraphic  currents, 
so  as  to  modify  their  rise  and  fall,  by  means  of  condensers 
and  electro- magnets.  The  difficulty  with  this  plan  is  that 
it  retards  telegraphy  ;  and  it  is  doubtful  whether  the  dis- 
advantages due  to  this  reason  will  not  more  than  compen- 
sate for  any  advantages  gained  by  the  invention. 

The  practical  applications  which  have  been  made  of  the 
telephone  to  various  purposes  are  legion.  One  of  the 
most  interesting  features  of  the  Paris  Electrical  Exhibition 
of  1881  was  a  room  fitted  up  with  some  eighty  telephone 
receivers  which  connected  with  an  assemblage  of  micro- 
phone transmitters  arranged  around  the  front  of  the  stage 
of  the  Grand  Opera.  Listeners  in  the  receiving- room 


314  THE  AGE  OF  ELECTRICITY. 

could  hear  the  music  with  perfect  distinctness ;  and  as 
each  person  was  provided  with  two  receivers  communicat- 
ing with  transmitters  placed  at  opposite  parts  of  the  stage, 
by  remarking  the  difference  in  loudness  of  the  sound  at 
either  ear  he  could  thus  in  a  measure  follow  the  move- 
ments of  the  singer  about  the  stage.  In  Brooklyn,  tele- 
phone transmitters  have  been  arranged  near  the  pulpits 
of  several  popular  preachers,  so  that  members  of  the 
congregation  unable  to  attend  may  listen  to  the  sermon 
in  their  own  dwellings. 

Two  very  beautiful  applications  of  the  telephone  have 
been  made  by  Professor  Hughes.     These  are  respectively 


Fig.  133. 


known  as  the  induction  balance  and  the  sonometer.  The 
induction  balance  is  illustrated  by  diagram  in  Fig.  133. 
The  current  from  a  small  battery  B,  connected  with  a  micro- 
phone 3/,  passes  through  two  coils  of  wire  Pl  P.r  wound  on 
bobbins  fixed  on  a  suitable  stand.  Above  each  of  these 
primary  coils  are  placed  two  secondary  coils  Sl  S2,  of  wire 
of  the  same  size  and  of  exactly  equal  numbers  of  turns  of 
wire.  The  secondary  coils  are  joined  to  a  telephone  T,  and 
are  wound  in  opposite  directions.  The  result  of  this  arrange- 
ment is  that  whenever  a  current  either  begins  or  stops  flow- 
ing in  the  primary  coil  Pl  it  induces  a  current  in  /6\,  and  P2 
in  /S'2.  As  £t  and  S.2  are  wound  in  opposite  directions,  the 
two  currents  thus  induced  in  the  secondary  wire  neutralize 


THE  SPEAKING   TELEPHONE.  315 

one  another ;  and,  if  they  are  of  equal  strength,  balance 
one  another  so  exactly  that  no  sound  is  heard  in  the  tele- 
phone. But  a  perfect  balance  cannot  be  obtained  unless 
the  resistances  and  the  co-efficients  of  mutual  induction 
and  self-induction  are  alike.  If  a  flat  piece  of  silver  or 
copper  (such  as  a  coin)  be  introduced  between  ^.and  Pl 
there  will  be  less  induction  in  St  than  in  S.2,  for  part  of 
the  inductive  action  in  Pl  is  now  spent  in  setting  up  cur- 
rents in  the  mass  of  the  metal,  and  a  sound  will  again  be 
heard  in  the  telephone.  But  balance  can  be  restored  by 
moving  S2  farther  away  from  P.2  until  the  induction  in  $2 
is  reduced  to  equality  with  Sv  when  the  sounds  in  the  tele- 
phone again  cease.  It  is  possible  by  this  means  to  test 
the  relative  conductivity  of  different  metals  which  are 
introduced  into  the  coils,  and  even  to  detect  a  counterfeit 
coin.  The  induction  balance  has  also  been  applied  in 
surgery,  to  detect  the  presence  of  a  bullet  in  a  wound ; 
for  a  lump  of  metal  may  disturb  the  induction  when  some 
inches  distant  from  the  coils.  Its  first  trial  as  a  bullet 
finder  was  in  the  case  of  President  Garfield  ;  but  unfortu- 
nately the  instrument  then  proved  of  little  avail,  as  it  was 
deceived  by  the  presence  of  metallic  springs  in  the  bed. 

The  sonometer  is  a  special  form  of  balance  for  examin- 
ing either  the  loudness  of  sounds,  or  the  capacity  of  any 
ear  for  distinguishing  sounds.  It  involves  an  ingenious 
arrangement  of  induction  coils  upon  a  graduated  rod, 
which  furnishes  a  scale  of  sensitiveness  of  hearing. 

Dr.  Boudet  has  succeeded  in  recording  automatically 
speech  reproduced  by  a  telephone  receiver,  by  removing 
the  diaphragm  and  substituting  a  delicate  armature  carry- 
ing a  stylus  which  made  tracings  on  smoked  paper.  Some 
similarities  between  the  sinuous  lines  traced  have  been 
detected,  but  there  is  evidently  much  to  be  discovered 
before  we  shall  be  able  to  read  the  telephone's  writing. 


816  THE  AGE  OF  ELECTRICITY. 

The  telephone  has  been  used  to  hear  the  mutterings  of 
earthquakes,  and  of  volcanoes  before  eruption.  It  has 
served  as  a  means  of  communication  from  earth  to  bal- 
loons, and  from  vessel  to  vessel  at  sea.  It  allows  watch- 
men on  the  surface  to  listen  to  the  operation  of  the  pumps 
in  deep  mines,  and  to  communicate  with  the  miners. 
Buried  in  the  earth,  it  has  proven  an  efficient  means  of 
detecting  subterranean  springs,  the  gurgle  of  which  is 
plainly  heard.  So  also  it  has  been  proposed  to  place 
microphones  on  the  picket-lines  of  armies  in  the  field, 
or  along,  roads  or  around  camps,  to  reveal  the  movements 
of  the  enemy.  It  is  employed  to  reveal  the  bodily  sounds, 
such  as  heart-murmurs  and  the  throbbing  of  the  pulse. 

In  1873  Mr.  Willoughby  Smith,  while  experimenting 
with  the  metal  selenium  as  a  means  of  measuring  large 
resistances  to  electric  currents,  discovered  that  the  mate- 
rial itself  was  very  sensitive  to  the  action  of  light,  which 
apparently  manifested  itself  by  causing  changes  in  the 
resistance  of  the  selenium.  One  of  the  first  practical 
applications  of  this  discovery  was  the  construction,  by  Dr. 
William  Siemens,  of  a  so-called  artificial  eye,  in  which  a 
selenium  plate  was  arranged  to  serve  as  a  retina,  upon 
which  a  lens  converged  the  light.  In  front  of  the  lens 
were  arranged  two  sliding  screens,  which  answered  to  lids  ; 
and  these  were  controlled  by  an  electro-magnet  in  circuit 
with  the  selenium,  with  which  also  a  galvanometer  was 
connected.  Whenever  the  lids  were  opened,  the  light 
falling  through  the  lens  upon  the  piece  of  selenium  caused 
a  variation  in  the  resistance  offered  by  the  latter  to  the 
electrical  current  passing  through  it,  so  that  any  changes 
in  the  intensity  of  the  light  were  shown  by  the  movement 
of  the  galvanometer  needle.  The  electro-magnet,  how- 
ever, was  adjusted  to  control  the  lids  automatically,  so 
that,  as  Dr.  Siemens  described  it,  here  was  "  an  artificial 


THE   SPEAKING    TELEPHONE. 


317 


eye,  sensitive  to  light  and  to  differences  in  color,  wtu'ch 
gives  signs  of  fatigue  when  it  is  submitted  to  the  prolonged 
action  of  light,  which  regains  its  strength  after  resting 
with  closed  lids,"  and  which  closes  its  lids  automatically 
on  the  occurrence  of  a  vivid  flash. 

Shortly  after  the  telephone  came  into  use,  Mr.  Smith 
connected  a  piece  of  selenium  with  the  instrument,  and 
then  for  the  first  time  actually  heard  a  ray  of  sunlight  fall 
upon  the  bar.  Others  had  conceived  of  the  same  idea, 
and  were  working  at  it ;  but  Professor  Bell,  in  conjunction 
with  Mr.  Sumner  Tainter,  was  probably  the  first  to  per- 


Flg.  134. 

feet  an  apparatus  to  transmit  speech  by  a  ray  of  light, 
and  to  realize  what  Professor  Bell  called  "  the  extraordi- 
nary sensation  of  hearing  a  beam  of  sunlight  laugh,  cough, 
and  sing,  and  talk  with  articulate  words."  This  appara- 
tus is  called  the  photophone.  It  is  operated  by  the  voice 
of  the  speaker  to  produce  variations  in  a  parallel  beam  of 
light,  corresponding  to  the  variations  in  the  air  produced 
by  the  voice. 

The  simplest  form  of  apparatus  consists  of  a  plane 
mirror  of  flexible  material,  such  as  silvered  mica  or 
microscopic  glass.  Against  the  back  of  this  mirror,  the 
speaker's  voice  is  directed,  a  speaking-tube  being  used  as 


318  THE  AGE   OF  ELECTRICITY. 

represented  in  the  diagram,  Fig.  134.  In  this  engraving 
B  is  the  transmitter  upon  which  the  mirror  M  reflects  a 
beam  of  light,  which  passes  through  a  lens  L,  and  then 
through  a  vessel  A  of  alum-water,  which  serves  to  cut  off 
the  heat-rays.  The  beam  reflected  from  the  mirror  M 
passes  through  a  lens  72,  and  then  travels  over  the  inter- 
vening space  to  a  parabolic  mirror  (7,  by  which  it  is 
reflected  and  concentrated  upon  the  selenium  cell  8. 
This  cell  is  included  in  circuit  with  a  battery  P  and  a  pair 
of  telephones  T  T. 

When  speech  is  uttered  into  the  speaking-tube  behind 
the  transmitter,  the  silvered  disk  is  alternately  bulged  out 
and  in,  and  in  this  way  it  becomes  more  or  less  concave 
or  convex  ;  the  degree  of  change  in  its  form  depending 
upon  the  variations  in  the  sound.  When  the  disk  is  most 
convex,  then  the  ray  reflected  from  it  will  be  most  widely 
scattered  or  diverged,  and  hence,  of  the  whole  beam,  a 
smaller  proportion  will  be  received  by  the  mirror  C.  Con- 
sequently the  amount  or  fraction  of  the  beam  of  light 
falling  upon  the  mirror  C  depends  upon  the  curvature  of 
the  disk,  which  in  turn  is  governed  by  the  speech-vibra- 
tions. Now,  the  more  light  falls  upon  the  mirror  (7, 
the  greater  the  quantity  converged  upon  the  selenium, 
and  hence  the  greater  the  conductivity  of  this  last  to  the 
battery  current  passing  through  it.  In  fine,  therefore, 
the  resistance  of  the  selenium  becomes  modified,  through 
the  medium  of  the  varying  light,  correspondingly  to  the 
sound-vibrations  of  speech ;  the  current  affected  by  pass- 
ing through  that  resistance  is  correspondingly  modified ; 
and  hence  the  original  sounds  are  reproduced  in  the 
telephone. 

Of  course  here  is  the  transmission  of  articulate  speech 
without  wires  of  any  sort,  and  simply  by  the  agency  of  a 
beam  of  light.  Over  how  great  an  interval  this  can  be 


THE  SPEAKING   TELEPHONE.  319 

clone,  is  not  yet  definitely  determined  :  the  longest  distance 
up  to  the  present  time  is  two  hundred  and  thirty-three 
yards. 

The  musical  or  direct  photophone  produces  sounds  from 
intermittent  beams  of  light.  The  beam  is  received  on  a 
mirror,  and  by  means  of  a  lens  brought  to  a  focus  upon 
a  disk  pierced  with  numerous  holes  arranged  in  a  circle. 
The  disk  is  rapidly  rotated,  —  from  one  to  five  or  six 
hundred  times  per  second,  —  and  the  light  passing  through 
the  holes,  and  thus  rapidly  interrupted,  is  converged  by  a 
lens  upon  a  disk  of  ebonite  from  which  extends  a  tube 
conveying  the  sounds  to  the  ear.  Disks  of  all  substances 
apparently  vibrate  under  the  interrupted  beam,  producing 
very  distinct  musical  sounds.  By  cutting  off  the  light  at 
any  moment,  by  an  opaque  screen  worked  by  a  telegraph- 
key,  Morse  signals  can  be  easily  sent.  Sounds  have  thus 
been  transmitted  for  distances  of  a  mile  and  somewhat 
over. 

What  improvements  the  future  will  bring  to  the  speak- 
ing telephone,  can  hardly  be  conjectured.  In  the  way  of 
loud-talking  receivers,  much  has  already  been  accom- 
plished of  which  the  public  knows  little.  Ordinary  re- 
ceiving telephones  can  be  made  to  talk  loud  enough  to 
be  easily  heard  throughout  a  good-sized  room,  and  at  a 
distance  of  thirty  or  forty  feet  from  the  instrument. 
Transmitters  are  already  sufficiently  sensitive  to  speech 
to  satisfy  all  practical  needs.  A  good  instrument  should 
easily  transmit  speech  uttered  twenty  feet  away  from  it. 
The  ordinary  commercial  instruments  will  not  do  this, 
simply  because  they  are  very  inferior  types.  The  great 
need  is  means  for  neutralizing  the  effects  of  induction, 
leakage,  retardation,  and  other  accidental  conditions  inci- 
dent to  all  lines.  When  that  is  accomplished,  there  should 
be  no  more  difficulty  in  talking  between  New  York  and 


320 


THE  AGE  OF  ELECTRICITY. 


San   Francisco   than    from    room    to    room    in   the    same 
building. 

In  May,  1886,  Mr.  Simmer  Tainter  patented  a  curious 
combination  of  phonograph  and  telephone,  which  is,  in 
fact,  an  electrical  phonograph.  The  phonograph,  as 
hitherto  known,  is  an  apparatus  for  mechanically  record- 
ing and  reproducing  sounds,  including  spoken  words. 
Although  it  is  very  frequently  described  in  electrical 
works,  it  is  not  in  any  sense  an  electrical  instrument.  The 
ordinary  form  of  phonograph,  as  devised  by  Mr.  T.  A. 
Edison,  is  represented  in  Fig.  135.  When  the  cylinder  A 
is  revolved  on  its  own  axis,  it  also  moves  laterally  ;  and, 


Fig.  135. 

while  it  is  thus  moving,  the  operator  talks  or  sings  into 
the  mouthpiece  B,  on  the  rear  side  of  which  is  a  thin 
plate  or  diaphragm,  which  carries  a  needle-point.  The 
plate  is  thus  thrown  into  vibration  ;  and  the  needle-point 
is  so  caused  to  make  an  indented  furrow  spirally  around  a 
sheet  of  soft  tin-foil  which  smoothly  envelops  the  cylinder. 
Under  a  magnifying-glass  this  furrow  looks  like  a  series 
of  very  minute  dots  ;  but  it  is  the  handwriting  of  the 
sound. 

After  the  foil  is  indented  as  described,  the  cylinder  is 
brought  back  to  its  original  position,  and  the  needle-point 
is  placed  at  the  beginning  of  the  line  of  dots.  Then  the 


THE  SPEAKING   TELEPHONE. 


321 


cylinder  is  revolved  as  before  ;  but  now  the  needle-point 
runs  over  and  into  the  elevations  and  depressions  made  in 
the  foil,  and  thus  the  thin  plate  carrying  the  point  is  set 
into  vibrations  which  reproduce  the  original  sounds. 

In  some  forms  of  mechanical 
phonograph,  in  place  of  the 
revolving  cylinder  A  a  rotat- 
ing flat  circular  disk  is  used, 
on  the  face  of  which  a  spiral 
line  of  indentations  is  pro- 
duced in  the  manner  already 
described.  Mr.  Tainter  uses 
such  a  disk,  which  he  covers  F'9'  136' 

with  wax  in  which  he  produces  his  indentations.  From 
this  wax-covered  disk  he  makes  an  electrotype  facsimile  ; 
and  then  using  his  electrotype  as  a  pattern  to  guide  an 
automatically  operating  cutting-tool,  he  reproduces  all  the 
dots  or  indentations  upon  the  crest 
of  a  spiral  ridge  which  is  formed 
on  the  face  of  a  disk  of  iron  or 
other  magnetic  material.  A  por- 
tion of  the  face  of  this  iron  disk 
is  shown  in  Fig.  136.  The  disk 
thus  prepared  is  called  a  "mag- 
netic record;"  and  it  is  mounted 
upon  a  shaft,  as  shown  in  edge 
view  in  Fig.  137,  by  which  it  is 
revolved  between  the  poles  of  a 
horse-shoe  magnet.  One  pole  of 
this  magnet  is  quite  close  to  the  rear 
side  of  the  disk  ;  the  other  pole  carries  a  needle,  the  point 
of  which  is  placed  very  near  to  the  indented  ridge  on  the 
disk,  but  does  not  touch  it.  In  the  mechanical  phono- 
graph, it  will  be  remembered,  the  needle  actually  follows 


if/Toft. 


Fig.  137. 


322  THE  AGE   OF  ELECTRICITY. 

the  line  of  dots.  Here  the  needle  is  entirely  separated 
from  the  indentations.  Hence,  because  the  needle  is  at- 
tached to  one  pole  of  the  magnet,  and  the  disk  is  very 
close  to  the  other  pole,  both  needle  and  plate  become  mag- 
netized by  induction  ;  and  as  they  are  at  opposite  poles  of 
the  magnet,  and, .besides,  are  very  close  together,  a  very 
strong  magnetic  field  exists  between  them.  Finally, 
around  the  needle  is  a  coil  of  wire,  the  ends  of  which 
are  connected  to  a  receiving  telephone  of  the  usual  form. 

The  reader  will  have  no  difficulty  here  in  recognizing  all 
the  parts  of  a  magneto-electric  machine  in  which  the  mag- 
net (disk)  revolves  in  front  of  the  core  (needle),  and  so 
induces  a  current  in  the  coil  surrounding  the  core.  Now, 
while  a  perfectly  smooth  circular  plate  magnet  might  be 
revolved  in  the  way  shown,  in  front  of  a  coil,  without 
causing  any  current  in  the  latter,  here  we  have  a  plate 
magnet  on  which  there  is  a  continuous  line  of  eleva- 
tions and  depressions  which  successively  pass  before  the 
needle-point.  Of  course  the  surface  of  the  magnet  at 
the  bottom  of  a  depression  is  farther  from  the  point  than 
is  the  surface  at  the  top  of  an  elevation.  Hence,  as  the 
magnet  revolves,  the  distance  of  its  surface  from  the  nee- 
dle-point is  constantly  changing,  and  therefore  changes  are 
produced  in  the  magnetic  field  around  the  needle-point ; 
and  hence  currents  are  set  up  in  the  coil  of  which  the  nee- 
dle is  the  core,  and  in  a  telephone  connected  with  the 
coil.  In  this  way^  the  telephone  is  made  to  reproduce 
the  sounds  which  in  the  beginning  caused  the  indentations 
in  the  waxed  plate. 

The  most  striking  feature  of  the  apparatus  lies  in  the 
fact  that  here  is  apparently  simply  an  iron  disk  revolving 
quite  slowly,  and  not  in  contact  with  any  thing.  A  little 
coil  of  wire  is  fastened  near  to  it,  and  a  telephone  is  in 
circuit  with  that  wire.  The  indented  foil  of  the  mechani- 


THE  SPEAKING    TELEPHONE.  323 

cal  phonograph,  being  rubbed  by  the  needle,  soon  wears 
out ;  and,  indeed,  after  three  or  four  repetitions  of  the 
sound,  the  articulation  becomes  very  much  blurred  if  not 
altogether  indistinct.  But  this  iron  disk  will  last  forever. 
There  is  no  frictional  contact  to  wear  it  out.  It  is  far 
more  durable  as  a  record  than  even  the  printed  page  ;  and, 
like  the  latter,  it  may  by  electrotyping  be  infinitely  re- 
duplicated. Who  knows  but  that  the  books  of  the  future 
will  be  made  in  this  way?  Imagine  the  author  dictating 
his  thoughts  to  the  slowly  revolving  waxed  plate,  and  fin- 
ally sending  them  to  the  world  in  the  form  of  an  iron 
plate.  And  then  the  reader  —  or,  rather,  the  hearer  — 
simply  goes  to  the  collection  of  plates  which  forms  his 
library,  selects  his  volume,  fastens  it  on  the  shaft  driven 
by  a  little  electro-motor,  touches  the  button  which  starts 
the  machine,  puts  his  telephone  to  his  ear,  and  listens  to 
the  author's  words  read  by  the  author,  and  so  given  the 
meaning  which  the  author  intended.  And  further,  by  per- 
haps a  little  stretch  of  fancy,  think  how  any  one  of  the 
noted  novelists  who  nowadays  delight  the  public  by  read- 
ings of  their  own  romances,  might,  so  to  speak,  expand 
himself.  He  might,  for  example,  discourse  each  of  his 
novels  before  a  separate  plate.  When  a  lecture-committee 
invites  him  to  the  platform, — in  lieu  of  a  disagreeable 
railroad-journey  taken  by  himself,  he  merely  forwards  the 
plate  of  the  desired  novel,  by  express.  It  is  the  plate 
which  comes  on  the  platform,  and  not  the  reader  — 
although,  no  doubt,  a  life-sized  photograph  of  the  author 
could  be  exhibited  to  add  to  the  illusion.  As  it  is  as 
easy  to  connect  a  hundred  telephones  as  one,  to  the  coil, 
there  the  audience  might  sit,  —  there  a  score  of  audiences 
might  sit,  in  as  many  different  towns  all  over  the  land,  — 
each  person  listening  through  his  own  telephone,  while 
the  dignified  functionary  who  usually  introduces  lecturers 


324  THE  AGE   OF  ELECTRICITY. 

might  also  turn  the  plate  by  a  foot- treadle,  regulate  the 
current,  and  acknowledge  the  applause. 

In  fact,  it  would  not  even  be  necessary  for  an  audience 
to  gather.  The  plate  would  probably  be  sent  directly  to 
the  central  office  of  the  local  telephone  exchange  ;  and  the 
subscribers  would  stay  at  home,  and  hear  the  lecture  or 
reading  over  the  lines. 

Of  course,  noted  singers  might  also  have  their  plates, 
and  the  plates  at  least  would  never  be  indisposed  and  un- 
able to  sing.  And,  as  for  congressmen,  to  them  the  in- 
vention might  prove  indeed  a  boon  ;  for  a  powerful  oration 
duly  impressed  on  a  magnetic  record  plate  could  techni- 
cally be  delivered  in  Congress  through  the  medium  of  a 
machine  which  would  revolve  the  disk  at  say  twenty  thou- 
sand revolutions  a  minute  ;  and  then  be  re-delivered  before 
one's  constituents  with  all  the  emphasis  to  be  got  out  of 
one  revolution  in  five  minutes. 

Fanciful  speculation,  however,  aside,  Mr.  Tainter's  in- 
vention is  of  much  ingenuity ;  and,  while  it  is  difficult  to 
predict  many  practical  every-day  applications  for  it,  that 
it  will  prove  stimulative  and  suggestive  to  further  research 
in  the  same  field,  is  certainly  to  be  expected. 


THE  INDUCTION  COIL.  325 


CHAPTER    XIII. 

THE  INDUCTION  COIL,  AND  POWERFUL  ELECTRIC  DISCHARGES. 

ALTHOUGH  machines  for  the  production  of  static  or 
f rictional  electricity  have  been  made  the  subject  of  many 
ingenious  improvements  within  recent  years,  they  have 
found  little  practical  application  out  of  the  laboratory  or 
lecture-room.  Wherever  discharges  of  high  potential  elec- 
tricity are  required,  the  same  can  be  much  more  conven- 
iently and  certainly  obtained  through  the  agency  of  the 
induction  coil.  Two  classes  of  static  electrical  machines 
are,  however,  recognized, — those  in  which  a  plate  or 
cylinder  of  glass  is  constantly  excited  by  friction,  and  as 
constantly  discharged  into  a  reservoir  of  force  ;  and  those 
in  which  the  electric  is  excited  by  friction  at  the  com- 
mencement of  the  operation,  but  is  not  itself  discharged. 
A  small  initial  charge  is  given,  for  example,  to  a  piece  of 
ebonite ;  and  a  revolving  glass  disk  is  thus  caused  to  re- 
ceive a  succession  of  charges  which  are  transferred  to  a 
condenser  or  conductor,  which  in  turn  re-acts  upon  the 
original  charge,  and  gradually  raises  it  to  a  high  tension. 

The  first  type  of  machine,  depending  entirely  upon  fric- 
tion, has  become  nearly  obsolete,  because  of  its  defects 
and  the  labor  of  working  it.  The  second  type,  known 
as  induction  machines,  produces  equal  effects  with  only  a 
fraction  of  the  mechanical  work.  The  latest  and  best 
forms  of  this  apparatus  are  those  devised  respectively 
by  Voss  and  Wimshurst. 


326  THE  AGE   OF  ELECTRICITY. 

Where  very  powerful  electrical  discharges  are  now  re- 
quired, they  are  produced  by  means  of  the  inductorium, 
or  induction  coil.  In  explaining  the  phenomena  of  induc- 
tion, and  Faraday's  great  discoveries  relating  thereto,  we 
noted  that  whenever  a  conductor  through  which  a  current 
was  passing  was  moved  into  proximity  to  another  con- 
ductor forming  a  closed  circuit,  an  induced  current  was 
caused  in  the  second  conductor ;  and  that  this  happened 
whether  the  first  conductor  was  moved  into  proximity  to 
the  second,  or  the  second  into  proximity  to  the  first ;  and 
this  was  illustrated  in  Fig.  43.  Now,  it  is  not  at  all 
necessary  to  move  either  conductor  in  order  to  induce  a 
current  by  one  in  the  other.  The  two  conductors  —  as,  for 
example,  the  two  coils  in  Fig.  43,  may  be  rigidly  fixed  in 
a  stationary  position,  and  the  current  itself  moved  into  or 
out  of  one  of  them  ;  that  is,  by  establishing  it  or  inter- 
rupting it.  By  this  arrangement  one  conductor  is  always 
in  the  magnetic  field  of  force  of  the  other ;  and  when  we 
make  or  break  the  current,  we  simply  produce  the  field  of 
force  or  cause  it  to  disappear.  Every  time  we  "make" 
the  circuit  in  the  so-called  primary  conductor  or  coil,  we 
induce  in  the  other,  or  secondary  conductor  or  coil,  a 
momentary  current  in  the  opposite  direction  ;  and  at  every 
break  of  the  primary  current,  a  powerful  secondary  cur- 
rent in  the  same  direction  is  caused. 

In  the  induction  coil,  there  are  two  coils  of  wire.  The 
primary  coil  is  made  of  larger  wire,  so  that  it  may  carry 
strong  currents,  and  produce  a  powerful  magnetic  field  at 
«;he  centre.  It  has  few  turns,  so  as  to  keep  the  resistance 
low,  and  to  prevent  the  inductive  action  of  the  turns  of  the 
coil  on  each  other.  Within  this  coil  is  an  iron  core,  which, 
becoming  itself  magnetized  by  the  current  passing  through 
the  primary  coil  which  immediately  surrounds  it,  increases 
the  number  of  lines  of  force  passing  through  the  coils. 


THE  INDUCTION  COIL.  327 

This  core  is  usually  made  of  a  bundle  of  straight  fine 
wires.  Finally,  wound  around  the  outside  of  the  primary 
coil  is  the  secondary  coil,  which  is  made  of  very  thin  wire 
in  an  immense  number  of  turns.  All  of  the  wire  is  very 
carefully  insulated,  so  that  the  currents  traverse  its  entire 
length.  Every  time  the  current  is  established  or  broken 
in  the  turns  of  the  primary  coil,  a  momentary  current  is 
induced  in  the  turns  of  the  secondary  coil ;  and  the  com- 
bined inductive  effect  of  the  turns  of  the  primary  coil, 
upon  the  immense  number  of  turns  of  the  secondary  coil, 
occurring  instantaneously,  results  in  a  current,  or  rather  a 
discharge,  of  enormous  electro-motive  force. 


Fig.  138. 

In  order  to  produce  the  necessary  rapid  interruptions  of 
the  current  in  the  primary  coil,  an  automatic  circuit- 
breaker  is  provided.  This  may  be  simply  a  vibrating 
armature  of  an  electro-magnet,  alternately  energized  and 
de-energized,  which  armature  in  vibrating  alternately  makes 
and  breaks  the  primary  circuit.  This  arrangement  is  used 
m  comparatively  small  induction  coils,  such  as  the  one 
illustrated  in  Fig.  138  ;  but  in  larger  machines,  such  as 
represented  in  P'ig.  139,  Foucault's  interrupter  is  used. 
This  consists  in  an  arm  of  brass  L,  which  dips  a  platinum 
wire  into  a  cup  of  mercury  M,  from  which  it  withdraws 
the  point,  so  breaking  circuit  in  consequence  of  its  other 
end  being  attracted  to  the  core  of  the  coil  whenever  the 


328 


THE  AGE  OF  ELECTRICITY. 


coil  is  magnetized.     When  the  coil  is  demagnetized  the 
arm  is  drawn  out  by  a  spring,  so  breaking  the  circuit. 

As  has  been  above  stated,  whenever  a  current  is  passed 
through  a  conductor,  it  acts  inductively  upon  itself,  pro- 
ducing a  current  which  is  known  as  the  extra  current. 
When  the  circuit  is  established,  this  extra  current  moves 
against  the  main  current,  diminishes  its  force,  and  pre- 
vents it  rising  to  its  full  value.  When  the  circuit  is 


Fig.  139. 

broken,  the  extra  current  moves  with  the  main  current, 
and  increases  the  strength  of  the  latter  just  at  the  moment 
when  it  ceases  altogether.  The  extra  current  in  the  pri- 
mary coil  of  an  inductorium  would  materially  interfere 
with  its  efficiency.  To  prevent  this,  it  is  usual  to  connect 
in  the  circuit  of  the  primary  coil  a  small  condenser,  made 
of  alternate  layers  of  tin-foil  and  paraffined  paper,  into 
which  the  current  flows  when  the  circuit  is  broken.  The 
effect  of  the  condenser  is  first  to  make  the  break  of  the 
circuit  more  sudden  by  preventing  the  spark  of  the  extra 


THE  INDUCTION  COIL.  329 

current  from  leaping  across  the  interrupter,  and,  second, 
to  accumulate  the  electricity  of  this  self-induced  extra 
current  in  order  that  when  circuit  is  again  made,  the 
current  shall  attain  its  full  strength  gradually  instead  of 
suddenly,  thereby  causing  the  inductive  action  in  the 
secondary  circuit  at  "make"  to  be  comparatively  feeble. 

In  the  arrangement  shown  in  Fig.  139,  the  battery  is  con- 
nected to  the  binding  posts  6,  b' ',  in  circuit  with  which  are 
a  commutator  at  C,  the  primary  wire  of  the  coil  which  is 
secured  to  the  posts  /,  /,  and  also  the  interrupter  or  break 
L,  M.  The  condenser  is  disposed  in  the  base  of  the  in- 
strument, and  connects  with  the  posts  /,  /.  So  that  the 
battery  current  flows  normally  through  the  primary  coil, 
is  broken  at  the  interrupter,  and  the  extra  current  due  to 
the  breaks  enters  and  is  diffused  in  the  condenser.  The 
ends  of  the  secondary  coil  connect  with  the  upper  ends 
of  the  glass  posts  at  A,  B,  and  between  the  terminals  of 
this  coil  the  discharge  or  spark  is  produced. 

The  most  powerful  induction  coil  in  existence  is  that 
constructed  by  Apps  for  the  late  Mr.  Spottiswoode.  The 
secondary  wire  is  280  miles  in  length,  and  contains  341,850 
turns.  With  thirty  Grove  cells  this  apparatus  is  compe- 
tent to  yield  a  spark  forty-two  inches  long  between  the 
terminals  of  the  secondary  coil.  These  terminals  are 
placed  above  the  coil,  in  the  same  position  as  the  termi- 
nals ^1  B  in  the  much  smaller  coil  represented  in  Fig.  139. 
The  sparks  produced  by  such  a  machine  as  this  are  verit- 
able flashes  of  lightning,  accompanied  by  reports,  which 
represent  the  thunder  in  miniature.  In  order  to  produce 
a  spark  forty-two  inches  in  length  from  a  galvanic  battery 
only,  it  has  been  calculated  that  from  sixty  thousand  to  a 
hundred  thousand  cells  of  the  most  favorable  construction 
would  be  required. 

Fig.  140  represents  the  great  Spottiswoode  coil.     The 


330  THE  AGE  OF  ELECTRICITY. 

discharge  occurs  between  the  disk  and  the  small  ball 
shown  immediately  in  front  of  the  cylinder,  and  usually 
appears  as  a  zigzag  line  of  bluish-white  light  accompanied 
by  both  a  crackling  and  a  hissing  sound.  When  the 
points  are  brought  within  some  two  or  three  inches  of 
each  other,  the  discharge  appears  as  a  mass  of  yellow 
flame  from  a  half  to  three-quarters  of  an  inch  thick.  The 
twenty-eight-inch  spark  will  perforate  a  piece  of  glass 
three  inches  in  thickness,  and  it  is  calculated  that  a  glass 
block  twice  as  thick  could  be  penetrated  by  the  forty-two- 
inch  spark. 

When  a  high-tension  discharge  of  electricity  is  sent 
through  rarefied  air  or  through  a  vacuum,  the  appearance 
of  the  spark  greatly  changes.  In  rarefied  air,  the  light 
assumes  a  red  glow,  and  a  beautiful  green  radiance  is  pro- 
duced when  a  part  of  the  glass  is  colored  with  uranium. 

Induction  coils,  of  course  on  a  small  scale,  are  used  in 
medical  electric  apparatus.  Their  most  important  practi- 
cal employment  is  in  connection  with  the  telephone  trans- 
mitter, wherein  the  coil  renders  the  working  current  from 
the  battery  of  greater  force,  and  so  enables  speech  to 
be  transmitted  over  longer  distances.  The  huge  coils 
above  described  have  proved  of  great  assistance  in  the 
study  of  the  behavior  of  the  electrical  current  in  rarefied 
media ;  and  a  very  elaborate  series  of  investigations  was 
made  by  Mr.  Spottiswoode,  by  the  aid  of  his  coil,  into 
the  nature  of  the  peculiar  striae  or  stratifications  into  which 
the  electric  discharge  separates  when  passed  through  nar- 
row tubes.  When  the  exhaustion  of  a  so-called  vacuum 
tube  is  carried  considerably  beyond  the  point  which  gives 
the  best  striae  and  luminous  effects,  a  new  set  of  phenom- 
ena is  produced ;  the  residual  gas  in  the  tube  developing 
so  many  new  and  curious  properties  that  Mr.  William 
Crookes,  F.R.S.,  has  asserted  that  the  gas  may  in  fact 


THE  INDUCTION  COIL.  331 

be  regarded  as  matter  in  a  fourth  or  ultra-gaseous  state. 
To  the  known  conditions  of  matter,  —  solid,  liquid,  and 
gaseous,  —  he  thus  adds  one  which  he  terms  "  radiant." 

Probably  the  most  important  application  of  static  or 
frictional  electricity  to  industrial  use  is  the  electric  mid- 
dlings-purifier devised  by  Messrs.  Smith  and  Osborne. 
This  consists  of  a  series  of  hard  rubber  rolls  electrified 
by  the  friction  of  hair,  silk,  wool,  or  other  suitable  mate- 
rial ;  under  which  rolls  the  middlings  pass  slowly  to  a 
shallow  receiver,  the  latter  being  rapidly  shaken  so  as  to 
bring  the  bran  to  the  top.  The  light  particles  of  bran 
leap  to  the  rolls,  and  cling  thereto  until  brushed  into  a 
shallow  gutter  placed  in  front  of  each  roll.  Meantime 
the  heavy  and  electrically  rejected  middlings  descend  by 
gravity,  and  pass  through  the  bolts  in  the  order  of  their 
fineness.  Travelling  brushes  constantly  sweep  the  bran 
from  the  gutters,  into  the  bran-receiver  on  the  side  of 
the  purifier.  In  this  receiver  is  a  spiral  conveyer.  By  the 
time  the  last  line  of  rolls  is  reached,  the  material  has 
been  successively  diminished  by  the  abstraction  of  the 
bran  and  the  screening  out  of  the  several  grades  of  mid- 
dlings, until  only  a  trifling  quantity  of  heavy  refuse  (if 
there  be  any)  is  left  to  pass  over  the  tail  of  the  purifier 
into  the  spout  provided  for  it.  The  bran  which  adheres 
to  the  rolls  is  brushed  off  when  it  reaches  the  sheepskin 
cushion,  which  lightly  touches  the  top  of  the  roll  to 
electrify  the  hard  rubber. 

The  curious  suggestion  has  been  made,  that  perhaps 
the  lightning  can  be  made  to  produce  artificial  diamonds 
through  the  volatilization  of  carbon  confined  in  an  im- 
mensely strong  vessel.  It  was  proposed  to  place  such  a 
vessel,  containing  some  form  of  carbon,  in  the  circuit  of 
a  lightning-rod,  so  that  the  current  would  necessarily  pass 
through  the  carbon  in  going  to  earth  ;  the  idea  being,  that 


332  THE  AGE   OF  ELECTRICITY. 

after  volatilization  the  carbon  would  perhaps  crystallize 
into  the  diamond.  This  seems  rather  more  fantastic  than 
practicable. 

The  discharge  of  statical  electric  machines  has  been 
found  very  efficacious  in  causing  the  deposition  of  smoke ; 
the  particles  forming  flakes,  and  rapidly  sinking.  Rooms 
filled  with  dense  smoke  have  thus  been  rapidly  cleared. 
A  useful  application  of  this  discovery  has  been  made  in 
effecting  the  condensation  of  volatilized  lead,  for  which 
purpose  long  passages,  some  two  miles  in  length,  are 
ordinarily  required. 

Whether  the  actual  lightning  discharge  will  be  utilized, 
remains  yet  to  be  seen.  Many  years  ago  Mr.  Andrew 
Crosse  erected  insulating  supports  throughout  his  grounds, 
and  on  these  stretched  three  thousand  feet  of  exploring 
wire,  by  means  of  which  the  electricity  of  the  air  could 
be  conveyed  into  the  house  and  there  examined.  When 
connection  was  made  with  the  inner  coating  of  his  great 
Ley  den-battery  of  fifty  jars,  exposing  146  square  feet  of 
coated  surface,  remarkable  effects  were  obtained.  Iron 
wire  ^fa  of  an  inch  thick  and  thirty  feet  in  length  was 
fused  into  red-hot  balls  ;  strips  of  metal  laid  on  glass, 
and  placed  in  circuit,  were  on  discharge  of  battery  instantly 
dissipated,  leaving  only  metallic  streaks. 


OTHER  APPLICATIONS   OF  ELECTRICITY.      333 


CHAPTER  XIV. 

THE    APPLICATIONS    OF    ELECTRICITY    TO    MEDICINE,    WAR, 
RAILWAYS,    TIME,    MUSIC,   ETC. 

THE  utilizations  of  electricity  reveal  the  most  singular 
contrasts.  It  is  a  vigilant  and  sleepless  sentinel :  it  guards 
the  signals  which  protect  the  swift-rushing  express  ;  it 
warns  us  of  the  inroad  of  thieves  or  the  outbreak  of  fire 
in  our  dwellings,  the  leak  in  the  vessel,  or  the  low  water 
in  the  steam-boiler.  On  the  other  hand,  it  is  a  most 
treacherous  foe :  it  drives  and  explodes  the  deadly  tor- 
pedo, which,  all  concealed  under  water,  steals  noiselessly 
upon  the  fated  ship  ;  it  fires  the  hidden  mine  beneath  the 
very  feet  of  the  unsuspecting  battalion  ;  and  from  its  inert, 
harmless-seeming  wires,  the  merest  casual  touch  may  bring 
forth  instant  death,  swift  as  the  greater  lightning,  Jn  the 
hands  of  the  physician,  the  curative  effects  of  the  electric 
current  render  it  a  potent  ally  for  the  relief  of  human  suf- 
fering :  yet  its  destructive  certainty  will  in  time  render  it 
the  instrument  of  execution  of  the  last  penalty  of  the  law. 

It  annihilates  time  and  space  in  the  telegraph ;  yet  it 
may  govern  the  one  in  hundreds  of  clocks  simultaneously, 
and  measure  the  other  as  it  is  traversed  by  the  railway- 
train  or  the  steamship.  It  will  impel  the  locomotive  ;  and, 
equally,  it  will  control  the  brake  which  stops  its  motion. 
It  will  deposit  the  flakes  of  the  smoke-cloud  ;  or  fire  the 
charge  which  hurls  aloft  whole  acres  of  rock,  and  opens 


334  THE  AGE   OF  ELECTRICITY. 

great  rivers  to  navigation.  It  will  light  up  the  inner  cav- 
ities of  the  living  body,  so  that  the  eye  of  the  surgeon 
may  explore  them  ;  or  illuminate  the  eternal  darkness  of 
the  depths  of  the  great  sea,  so  that  the  retina  of  the  cam- 
era may  see  and  record  their  mysteries.  It  will  indicate 
for  us  the  heat  of  the  steel-furnace,  or  that  of  the  far 
distant  stars.  In  one  form  it  will  tear  asunder  the  atoms 
of  water ;  in  another,  cause  them  to  re-unite.  It  will  set 
type,  and  drive  the  printing-press ;  operate  the  intricate 
pattern-mechanism,  and  move  the  loom.  It  is  already  in 
use  to  control  the  warmth  of  the  hatching  egg  :  it  has  been 
proposed  to  use  the  current  to  cremate  the  bodies  of  the 
dead.  It  will  protect  a  freezing-chamber  from  too  high 
a  temperature,  or  a  vineyard  from  the  effects  of  frost.  It 
will  make  engravings  and  etchings,  and  then  reproduce 
its  work  ad  infinitum.  It  will  aid  in  dyeing  and  in  bleach- 
ing. It  will  reveal  the  approach  of  the  earthquake  or  the 
rumblings  of  the  volcano,  or  the  almost  imperceptible 
sounds  of  the  human  heart.  It  will  steer  a  ship,  and  indi- 
cate her  course.  It  will  give  to  new  wine  the  flavor  of 
the  oldest  vintages.  It  will  ring  the  chimes  in  the  steeple, 
or  the  bells  in  the  kitchen.  It  will  turn  on  the  gas  in  our 
dwellings,  light  it  for  us,  and  turn  it  off.  It  will  record 
the  votes  which  change  the  destiny  of  a  great  nation,  or 
set  down  the  music  of  the  last  popular  melody.  It  will 
talk  in  our  voices,  hundreds  of  miles  away.  It  will  forge 
in  San  Francisco  the  signature  we  make  in  New  York, 
From  the  great  organ  it  will  evoke  all  its  majestic  har- 
monies, and  yet  set  free  the  tumult  of  whole  broadsides 

of  those 

"  Mortal  engines  whose  rude  throats 
The  immortal  Jove's  dread  clamors  counterfeit." 

Where  in  the  history  of  all  magic  are  there  wonders 
greater  than  these  ? 


OTHER  APPLICATIONS   OF  ELECTRICITY.      335 

And  we  can  do  no  more  than  suggest  their  vast  multi- 
plicity. To  attempt  to  compile  even  a  mere  list  of  the 
various  applications  of  electricity  to  specific  purposes, 
might  well  prove  a  hopeless  task ;  for,  if  fairly  compre- 
hensive to-day,  to-morrow  might  find  it  behind  the  times. 
There  is  no  exaggeration  in  the  statement :  the  record  of 
the  hundreds  of  patents  issuing  weekly  from  the  Patent 
Office  of  this  country  will  amply  substantiate  it,  and  the 
files  of  the  many  technical  periodicals  will  furnish  super- 
abundant proof.  Since  the  first  pages  of  this  work  were 
written,  a  few  months  ago,  Professor  Hughes  has  an- 
nounced the  results  of  his  discoveries  in  the  nature  and 
character  of  electrical  conductors,  which,  if  not  likely  to 
engage  popular  attention,  are  fairly  revolutionary  of  former 
ideas,  and,  in  point  of  scientific  interest  and  economic 
importance,  can  hardly  be  over-estimated.  So  also,  since 
then,  the  first  announcement  has  come  of  the  possibility 
of  the  direct  conversion  of  heat  into  electricity  in  the 
galvanic  cell,  using  no  temperature  above  that  of  boiling 
water,  —  a  discovery  great  in  its  potency  of  future  benefits, 
for  it  may  mark  the  beginning  of  the  end  of  the  reign  of 
steam. 

The  medical  use  of  electricity  —  electro-therapeutics  — 
belongs  to  the  domain  of  the  specialist  physician.  In  the 
hands  of  the  skilful  practitioner,  electricity  as  a  curative 
agent  often  proves  of  incontestable  value.  A  discussion 
of  even  the  elementary  principles  of  this  branch  of  the 
science  would  be  out  of  place  in  these  pages  ;  so  that  we 
restrict  ourselves  simply  to  some  of  the  more  curious  and 
salient  facts  attending  the  influence  of  electricity  in  and 
upon  the  animal  economy.  It  is  now  believed  that  the 
production  of  electricity  is  constant  in  all  the  living  tissues. 
Electrical  currents  occur  in  the  muscles  and  nerves,  and 


336  THE  AGE   OF  ELECTRICITY. 

between  different  surfaces  of  the  body.  All  of  the  bodily 
organs  yield  electrical  currents  when  they  are  divided. 

It  is  well  known  that  electricity  can  be  tasted.  A  cop- 
per coin  and  a  silver  coin,  placed  respectively  above  and 
below  the  tongue,  will  produce  a  sharp  acrid  flavor  very 
easily  recognized.  An  ingenious  telegrapher  once  suc- 
ceeded in  receiving  messages  sent  to  a  wrecked  railroad- 
train  in  this  way.  After  the  accident,  which  occurred  at 
a  long  distance  from  any  station,  the  telegraph-wires 
beside  the  road  were  cut,  and  a  message  easily  sent  by 
alternately  making  and  breaking  contact  of  one  end  of 
the  wire  with  the  other.  There  was,  of  course,  no  receiv- 
ing instrument  available  ;  but  the  ingenious  operator  sim- 
ply placed  the  ends  in  his  mouth,  and  —  as  the  story  goes 
—  managed  to  read  the  signals  sent  him,  simply  by  the 
recurrence  of  the  acrid  galvanic  taste. 

It  further  appears  that  the  current  is  capable  at  least 
of  stimulating  the  senses  of  smell,  hearing,  and  sight. 
Hitter  discovered  that  a  feeble  current  transmitted  through 
the  eyeball  produces  the  sensation  as  of  a  bright  flash  of 
light.  Curiously  enough,  on  the  other  hand,  it  has  been 
proved  that  when  a  frog's  eye  is  exposed  to  light,  a  cur- 
rent is  produced  in  the  optic  nerve.  A  strong  current 
causes  in  some  people  the  perception  of  blue  and  green 
colors  flowing  between  the  forehead  and  the  hand.  Volta 
and  Ritter  heard  musical  sounds  when  a  current  was 
passed  through  the  ears  ;  and  Humboldt  found  a  sensa- 
tion to  be  produced  in  the  organs  of  smell  when  a  current 
was  passed  from  the  nostril  to  the  soft  palate. 

Quite  an  effective  battery  has  been  made  from  frogs' 
thighs,  and  it  has  been  determined  that  the  electro-motive 
force  of  a  current  from  a  frog's  muscle  equals  about  -J  of 
a  volt.  When  properly  prepared,  the  legs  of  a  frog  con- 
stitute a  galvanometer  which  will  reveal  excessively  deli- 


OTHEE  APPLICATIONS  OF  ELECTRICITY.      337 

cate  induction  currents  barely  recognizable  by  the  most 
sensitive  instruments.  The  effect  of  electrical  currents  on 
newly  killed  animals  is  very  remarkable.  A  grasshopper 
has  thus  been  made  to  emit  its  chirp  ;  fishes,  sheep,  oxen, 
and  rabbits  undergo  spasmodic  muscular  contractions. 
Strong  currents  applied  to  the  bodies  of  executed  crimi- 
nals have  produced  contortions  of  the  most  horrible  char- 
acter, and  evoked  motions  of  the  members  and  organs 
almost  identical  with  those  of  life.  The  power  of  con- 
tracting under  the  influence  of  the  current  appears  to  be  a 
distinguishing  property  of  protoplasm  wherever  it  occurs. 
The  amoeba,  the  most  structureless  of  organisms,  suffers 
contractions  ;  and  the  sensitive-plant,  and  the  Dionaea  or 
Venus's  fly-trap,  both  close  when  electrified.  In  the  liv- 
ing human  body,  the  contraction  of  muscles  produces  cur- 
rents. These  Dubois-Reymond  obtained  from  his  own 
muscles  by  dipping  the  tips  of  his  fore-fingers  into  two 
cups  of  salt  water  communicating  with  the  galvanometer 
terminals.  A  sudden  contraction  of  the  muscles  of  either 
arm  produced  a  current  from  the  contracted  toward  the 
uncontracted  muscles. 

"It  appears,"  says  Dr.  Golding  Bird,  "that  we  are 
constantly  generating  this  agent,  and  that  quoad  the  sup- 
ply of  electric  matter  in  man  far  exceeds  the  torpedo  or 
the  electric  eel,  and  is  only  prevented  from  emitting  a  be- 
numbing shock  whenever  he  extends  his  hand  to  greet  his 
neighbor,  from  the  absence  of  special  organs  for  increas- 
ing its  tension.  .  .  .  Some,  indeed,  have  gone  the  danger- 
ous length  of  regarding  electricity  as  the  principle  of  life 
itself,  and  have  dared  to  place  it  on  a  level  with  the  divine 
essence,  which,  emanating  from  the  Creator,  constitutes 
what,  for  want  of  a  better  name,  we  call  vitality.  These 
pretensions  have  been  given  to  this  agent  from  its  effects 
when  made  to  traverse  the  muscles  of  recently  killed 


338  THE  AGE  OF  ELECTRICITY. 

animals,  but  more  particularly  when  conveyed  along  the 
spinal  nerves  of  a  recently  executed  malefactor.  This, 
in  the  hands  of  Dr.  Ure  in  his  celebrated  experiment  upon 
the  murderer  Clydesdale,  worked  on  the  dead  but  yet 
warm  corpse  a  horrible  caricature  of  life :  by  calling  into 
violent  contractions  the  muscles  of  the  face,  all  the  ex- 
pressions of  rage,  hatred,  despair,  and  horror,  were  de- 
picted upon  the  features,  producing  so  revolting  a  scene 
that  many  spectators  fainted  at  the  sight.  But  this  ex- 
periment, striking  as  it  was,  merely  afforded  an  additional 
proof  of  the  susceptibility  of  the  muscles  to  the  stimulus 
of  the  electric  current ;  and,  when  divested  of  its  dramatic 
interest,  becomes  not  more  remarkable  than  the  first  ex- 
periment of  Galvani  on  the  leg  of  a  frog." 

The  natural  currents  of  the  body  will  readily  affect  the 
telephone,  the  making  and  breaking  of  a  muscular  current 
being  plainly  perceptible  in  the  instrument.  M.  Boudet 
of  Paris  has  even  used  the  telephone  as  a  means  of  hear- 
ing the  workings  of  the  muscles  in  certain  paralytic  and 
nervous  ailments ;  while  the  resistance  telephone,  or  mi- 
crophone, has  proved  to  be  a  stethoscope  capable  of 
revealing  murmurs  in  the  circulation  which  cannot  be 
detected  by  the  ordinary  instrument. 

There  are  always  a  vast  number  of  so-called  electrical 
appliances  in  the  market,  in  the  shape  of  "electric" 
brushes,  "electric"  garments,  "electric"  belts,  etc. 
Whatever  curative  value  lies  in  these  things  resides  mostly 
in  the  imagination  of  the  user.  Many  of  them  are  wholly 
incapable  of  producing  any  electrical  effect  whatever  upon 
the  body.  It  is  a  safe  rule,  never  to  attempt  the  use  of  elec- 
tricity remedially,  save  under  the  advice  of  a  regular  phy- 
sician ;  for,  in  certain  bodily  ailments,  the  current  wrongly 
employed  may  be  productive  of  great  and  lasting  injury. 

Some  of  the  delusions  about  the  curative  effects  of  elec- 


OTHER  APPLICATIONS   OF  ELECTRICITY.      339 

tricity  have  been  very  singular  and  amusing  ;  and  perhaps 
the  first  of  them  furnishes  as  good  an  instance  as  any  of 
the  extraordinary  credulity  with  which  they  have  been 
received,  not  only  by  the  general  public,  but  often  by 
men  really  learned  in  science.  In  the  year  1747  Signior 
Johannes  Francisco  Pivati,  a  "person  of  eminence"  in 
Venice,  propounded  the  remarkable  theory,  that  if  odorous 
substances  were  confined  in  a  glass  vessel,  and  the  vessel 
electrically  excited,  the  odors  "and  other  medicinal  vir- 
tues "  would  transfuse  through  the  glass,  and  permeate 
the  person  holding  the  vessel ;  and  from  the  person  so 
permeated,  all  manner  of  diseases,  like  exorcised  spirits, 
would  at  once  depart,  while  the  individual  himself  would 
be  delightfully  perfumed.  In  this  absurdity  even  so  emi- 
nent a  philosopher  as  Winkler  of  Leipsic  firmly  believed ; 
and  then,  not  content  with  merely  believing,  he  proceeded 
to  improve  upon  Pivati's  stories  in  a  way  that  must  have 
disheartened  any  one  who  had  hitherto  believed  in  him. 
He  said  that  he  had  not  only  perfumed  a  whole  company 
with  cinnamon  ;  but  that  by  merely  connecting  a  globe 
filled  with  balsam,  by  means  of  a  long  chain  extending 
from  the  globe  to  his  patient,  the  latter's  "  nose  was  filled 
with  a  sweet  smell,  and  after  sleeping  in  a  house  a  con- 
siderable distance  from  the  room  where  the  experiment 
was  tried,  he  rose  very  '  chearful '  in  the  morning,  and 
found  a  more  pleasant  taste  than  ordinary  in  his  tea." 
Think  of  the  transmission  of  perfumes  by  telegraph ! 
The  Royal  Society  sent  to  Winkler  for  tubes,  and  invited 
him  to  repeat  some  of  his  alleged  wonderful  results.  But 
he  found  it  inexpedient  to  try.  Benjamin  Franklin  dealt 
the  finishing  stroke  to  the  humbug,  by  a  series  of  experi- 
ments which  clearly  demonstrated  the  entire  "  improbabil- 
ity of  mixing  the  effluvia  or  virtue  of  medicines  with  the 
electric  fluid." 


340  THE  AGE   OF  ELECTEICITY. 

Frequently  during  the  last  century,  and  even  occasionally 
nowadays,  persons  have  been  brought  before  the  public 
as  possessed  of  wonderful  inherent  electrical  properties. 
Sometimes  they  merely  transmit  disagreeable  shocks  to 
individuals  who  approach  them  ;  and  at  others,  they  con- 
tent themselves  with  performing  extraordinary  feats  of 
strength,  which  are  attributed  to  "electricity"  somewhere 
in  or  about  the  performer.  There  was  Angelique  Cotton 
of  Finisterre,  France,  who  in  1846  is  said  to  have  thrown 
down  powerful  men,  and  to  have  taken  chairs  away  from 
the  strongest  athletes.  The  chronicle  says  that  her  neigh- 
bors had  her  exorcised  without  avail,  and  that  she  was 
4 '  most  electric  after  dinner."  At  the  present  time  elec- 
tric boys  flourish  chiefly  in  dime-museums,  where  the  de- 
ception is  quite  neatly  done.  A  strong  battery  usually 
communicates  with  the  metal  plate  on  which  the  boy 
stands,  and  with  a  similar  metal  plate  on  the  other  side  of 
a  railing  before  which  the  visitor  must  place  himself  in 
observing  the  phenomenon.  When  the  visitor  touches  the 
boy,  circuit  is  made  through  the  bodies  of  boy  and  visitor, 
and  both  receive  a  shock.  The  boy  is  used  to  it,  and 
bears  the  infliction  stoically :  the  visitor,  who  is  just  as 
electric  as  the  show  itself,  experiences  a  spasmodic  con- 
traction, and  departs  much  gratified.  Some  visitors  have 
been  thoughtless  enough  to  present  their  knuckles  to  the 
lobes  of  the  ears  or  the  ends  of  the  noses  of  electric  boys, 
with  the  result  of  causing  to  the  phenomenon  much  bodily 
misery,  not  to  mention  some  interference  with  the  orderly 
and  peaceful  progress  of  the  entertainment. 

Very  powerful  electric  currents  will  cause  death  as 
instantaneous  as,  and  in  all  respects  similar  to,  that  due 
to  the  lightning  stroke.  Several  fatal  accidents  have 
occurred  through  workmen,  engaged  in  adjusting  electric 
lights,  grasping  the  ends  of  wires  leading  to  the  dynamos  ; 


OTHER  APPLICATIONS  OF  ELECTRICITY.      341 

and  there  have  been  many  instances  where  people  having 
incautiously  touched  the  brushes  of  dynamos  in  motion 
have  been  instantly  killed.  Professor  Tyndall  once,  while 
lecturing,  accidentally  received  the  discharge  of  a  large 
battery  of  Leyden-jars  ;  which,  he  says,  first  caused  a 
complete  obliteration  of  consciousness,  and  then  the  curi- 
ous sensation  of  a  floating  body  to  which  the  several  mem- 
bers were  one  by  one  attached,  until  he  finally  recognized 
that  he  was  all  there,  and  resumed  his  normal  condition. 
No  permanently  injurious  effects  followed. 

It  appears  to  be  demonstrated,  that  death  by  the  electric 
shock  is  painless,  for  the  reason  that  the  nerves  do  not 
have  time  to  convey  the  sense  of  the  injury  to  the  brain 
before  life  is  extinct.  The  substitution  of  the  electrical 
shock  for  the  present  inefficient  and  demoralizing  mode  of 
enforcing  the  death-penalty,  is  strongly  advocated;  and 
there  is  little  reason  to  doubt  that  in  time  it  will  be  effected. 
A  bill  to  this  end  was  introduced  in  the  New-York  Legis- 
lature in  1886.  With  electric-light  conductors  conveying 
deadly  currents  throughout  the  streets,  it  would  be  a  very 
easy  matter  to  carry  branches  of  these  to  the  usual  place 
of  execution,  and  despatch  the  criminal  instantly,  cer- 
tainly, and  painlessly,  by  the  mere  touch  of  a  button.  It 
is  said  that  a  current  of  a  strength  of  one-tenth  ampere 
is  as  much  as  any  one  can  safely  allow  to  traverse  his 
body  in  the  period  of  one  second  ;  and  this  strength  will 
depend  upon  the  bodily  resistance,  which  varies  between 
six  thousand  and  fifteen  thousand  ohms,  depending  mate- 
rially upon  the  condition  of  the  skin,  whether  moist  or  dry. 

There  has  been  one  application  of  electricity  to  slaugh- 
tering purposes,  not  only  proposed  but  patented.  On 
March  30,  1852,  a  United-States  patent  was  granted  to 
Dr.  Albert  Sonnenburg  and  Philipp  Rechten,  of  Bremen, 
Germany,  for  an  electric  whaling- apparatus,  which  is  not 


342  THE  AGE  OF  ELECTRICITY. 

without  ingenuity,  however  impracticable  it  doubtless  is. 
The  whale  is  harpooned  in  the  usual  way,  but  to  the  iron  is 
connected  a  stout  metallic  cable  leading  to  a  hand  magneto 
machine  in  the  whale-boat.  The  bottom  of  the  boat  is 
well  coppered.  As  soon  as  the  harpoon  has  struck,  the 
pole  is  withdrawn  so  that  the  head  of  the  harpoon,  together 
with  the  metallic  conductor,  remains  in  the  animal.  "The 
machine,"  say  the  inventors,  "is  now  set  in  motion;  the 
electric  current  through  the  metallic  conductor  and  the  head 
of  the  whale-iron  circulates  in  the  body  of  the  fish  or  ani- 
mal, and  returns  from  the  same  through  the  salt  water  to 
the  copper  bottom  of  the  boat,  and  thence  by  means  of  a 
short  metallic  conductor  to  the  machine.  The  fish  or  ani- 
mal receives  about  eight  tremendous  strokes  at  each  turn- 
ing of  the  machine  handle."  The  inventors  fail  to  explain 
what  inducement  is  offered  to  the  crew  of  the  boat,  to 
make  them  relinquish  their  oars,  and  turn  a  crank,  during 
the  rather  critical  moments  when  their  craft  is  moored  to 
a  wild  whale. 

Several  species  of  creatures  inhabiting  the  water  have 
the  power  of  producing  electric  discharges  by  certain  por- 
tions of  their  organism.  The  best  known  of  these  are  the 
torpedo,  the  gymnotus,  and  the  silurus,  found  in  the  Nile 
and  the  Niger.  The  raia  torpedo,  or  electric  ray,  of  which 
there  are  three  species  inhabiting  the  Mediterranean  and 
the  Atlantic,  is  provided  with  an  electric  organ  on  the 
back  of  its  head.  This  organ  consists  of  laminae  com- 
posed of  polygonal  cells  to  the  number  of  eight  hundred 
or  a  thousand,  or  more,  supplied  with  four  large  bundles  of 
nerve-fibres  :  the  under  surface  of  the  fish  is  negative,  and 
the  upper  positive.  In  the  gymnotus  electricus,  or  Surinam 
eel,  the  electric  organ  goes  the  whole  length  of  the  body, 
along  both  sides.  It  is  able  to  give  a  most  terrible  shock, 
and  is  a  formidable  antagonist  when  it  has  attained  its  full 


OTHER  APPLICATIONS  OF  ELECTRICITY.      343 

length  of  from  five  to  six  feet.  Humboldt  gives  an  inter- 
esting account  of  the  combats  between  the  electric  eels 
and  the  wild  horses,  driven  by  the  natives  into  the  swamps 
inhabited  by  the  gymnotus.  Prof.  S.  P.  Thompson  has 
called  attention  to  the  curious  point  that  the  Arabian  name 
for  the  torpedo,  ra-ac7,  signifies  lightning. 

Electrical  apparatus  for  aiding  medical  diagnosis,  or  for 
surgical  purposes,  exists  in  many  ingenious  forms.  The 
so-called  dental  engines,  for  actuating  the  burrs  and  other 
implements  used  in  operations  on  the  teeth,  are  now  driven 
by  small  electric  motors.  A  still  smaller  engine  is  con- 
cealed in  the  handle  of  the  plugger  which  compacts  the 
gold  fillings  in  teeth  ;  so  that  the  instrument  need  only  be 
placed  in  position,  and  the  work  usually  done  by  the  den- 
tist's assistant  with  a  mallet  is  automatically  accomplished. 
An  instrument  containing  a  minute  platinum  wire,  rendered 
white  hot  by  the  current,  is  employed  as  a  substitute  for 
the  needle  in  the  destruction  of  nerves.  A  truly  diaboli- 
cal contrivance  of  an  English  dentist  is  an  arrangement 
of  extracting- forceps  and  a  battery,  so  contrived,  that, 
as  the  tooth  is  removed,  a  severe  shock  is  administered  to 
the  victim.  The  peculiar  benefit  of  this  device  appears 
to  reside  in  the  fact  that  the  patient  is  hurt  so  much  by 
the  shock,  that  he  fails  to  notice  the  less  pain  involved 
in  the  actual  extraction  of  the  tooth.  The  electric  light 
is  a  valuable  aid  to  the  dentist.  Miniature  incandescent 
lamps  are  arranged  with  mirrors,  so  that  they  can  be  in- 
serted in  the  mouth,  and  their  rays  directed  at  will.  The 
oral  cavity  is  illuminated  so  brilliantly  that  any  departure 
from  normality  can  easily  be  detected,  while  the  light 
transmitted  through  the  teeth  reveals  with  much  clearness 
any  evidence  of  unsoundness. 

As  dental  fillings  often  consist  of  different  metals,  — 
such  as  silver,  tin  amalgam,  and  gold, — electrical  cur- 


344  THE  AGE  OF  ELECTRICITY. 

rents  are  frequently  set  up  between  them,  the  natural 
liquids  of  the  mouth  forming  the  conducting  fluid.  In 
such  cases,  gradual  wearing-away  of  the  attacked  metal 
follows  ;  and  instances  have  been  known  where  unaccount- 
able aches  in  filled  teeth  have  been  cured  by  removing  a 
filling  of  one  metal,  and  substituting  an  inert  substance  or 
a  metal  of  different  electrical  character. 

In  surgery,  fine  platinum  wires  highly  heated  by  the  cur- 
rent are  used  for  cauterizing  purposes,  and  for  the  removal 
of  abnormal  growths.  The  gastroscope  consists  of  a  rigid 
horizontal  tube,  terminating  in  one  direction  in  an  eye- 
piece, and  in  the  other  prolonged  into  a  partially  flexible 
tube  which  can  be  passed  down  the  oesophagus  until  its 
end  reachv-s  the  stomach.  At  the  end  of  the  tube  is  a 
tiny  glass  lantern,  in  which  is  a  piece  of  platinum  wire 
which  is  rendered  brilliantly  incandescent  by  the  current. 
From  this,  light  radiates  freely  on  all  sides,  and  illuminates 
the  interior  of  the  stomach.  In  the  tube  above  the  lan- 
tern is  a  little  window.  Into  this  a  portion  of  the  rays 
from  the  lantern  are  reflected  back  by  the  sides  of  the 
stomach.  Finally  there  is  a  very  ingenious  arrangement 
of  lenses  and  prisms,  whereby  the  image  of  the  side  of 
the  stomach  is  reflected  back  to  the  observer's  eye  at  the 
eye-piece  of  the  tube.  The  extremity  of  the  gullet  tube, 
with  its  little  window,  can  be  made  to  revolve,  so  that, 
after  the  instrument  is  once  adjusted,  the  operator  can 
easily  inspect  the  different  parts  of  the  interior  of  the 
stomach. 

The  laryngoscope  consists  simply  of  a  tongue  depresser, 
on  the  end  of  which  is  mounted  a  small  incandescent 
lamp.  It  is  used  for  examining  the  interior  cavities  of 
the  nose  and  mouth.  The  light  has  also  been  usefully 
employed  in  photographing  the  larynx.  The  photographic 
apparatus,  which  is  quite  small,  is  brought  into  position, 


OTHER  APPLICATIONS   OF  ELECTRICITY.      345 

and,  by  the  pressure  of  the  finger  on  a  button,  the  elec- 
tric circuit  is  closed  through  both  a  small  lamp  and  rn 
electro-magnet.  The  lamp  illuminates  the  parts  to  be 
photographed,  and  the  magnet  opens  the  objective,  so 
that  the  photograph  is  instantly  taken  on  very  sensitive 
prepared  plates. 

Trouve's  electric  probe  consists  of  three  distinct  parts, 
—  a  battery,  a  probe,  and  an  indicator.  The  probe  proper 
is  a  pipe,  flexible  or  rigid,  constructed  so  that  the  pre- 
liminary probing  may  be  effected,  and  then  the  stylets  of 
the  indicating  apparatus  introduced.  The  indicator  con- 
tains in  its  interior  a  very  small  electro-magnet  with  a 
vibrator  in  connection  with  two  steel  rods  which  pass  into 
the  body  of  the  probe  tube.  These  rods  are  insulated 
from  each  other,  so  that,  as  soon  as  they  touch  any 
metallic  body  in  the  wound,  circuit  is  thereby  established 
through  them,  and  the  vibrator  moves,  thus  revealing  the 
fact. 

The  induction  balance  has  also  been  applied  to  the 
detection  of  metallic  substances  in  the  body.  It  was 
used,  it  will  be  remembered,  unsuccessfully  in  the  case  of 
President  Garfield.  Professor  Bell  has  devised  another 
method  of  ball-finding,  which  involves  the  insertion  of  a 
needle  near  where  the  ball  is  supposed  to  be.  This  needle 
being  connected  by  wire  with  one  terminal  of  a  telephone, 
while  a  metallic  plate  laid  on  the  skin  is  connected  with 
the  other  terminal,  when  the  point  of  the  needle  reaches 
the  ball  a  current  arises  (the  ball  and  metallic  plate  natur- 
ally forming  a  couple),  and  a  sound  is  heard  in  the  tele- 
phone. The  needle  may  be  inserted  in  several  places, 
with  little  pain,  and  even  this  may  be  reduced  by  ether 
spray. 

It  has  been  proposed  to  use  the  thermo-pile  for  measur- 
ing bodily  temperatures  with  accuracy ;  and  a  system  has 


346  THE  AGE  OF  ELECTRICITY. 

even  been  suggested,  whereby  a  physician  sitting  in  his 
office  can  observe  the  temperature  of  his  entire  circle  of 
fever-patients  successively,  by  simply  connecting  by  tele- 
graph-lines each  one  in  turn  with  a  galvanometer  suitably 
disposed  on  his  desk,  —  after  which  he  might  telephone 
back  his  instructions  or  prescriptions  to  the  several  attend- 
ants. It  is  not  without  the  bounds  of  probability,  that 
some  one  will  yet  devise  an  alarm  contrivance  which  will 
automatically  call  up  the  physician  whenever  a  patient's 
temperature  reaches  a  certain  danger  point. 

The  applications  of  electricity  to  military  uses  bid  fair 
to  do  much  toward  the  revolution  of  modern  systems  of 
warfare.  The  electric  light  is  of  great  utility,  both  afloat 
and  ashore.  Its  beam  swept  around  the  horizon  reveals 
the  approach  of  an  enemy,  or  lights  up  fortifications  so 
that  a  bombardment  may  be  unerringly  directed  upon 
them.  Flashed  in  the  faces  of  an  attacking  force,  it  is 
bewildering.  On  board  of  vessels  of  war,  it  is  of  espe- 
cial utility  in  illuminating  the  sea  around  the  ship,  thus 
revealing  the  approach  of  torpedo-boats.  It  may  be  car- 
ried up  by  balloons  and  thus  employed  for  reconnoitring. 
Incandescent  lights  have  been  used  for  night  signalling, 
the  signals  being  indicated  by  rapid  extinctions  and  illu- 
minations according  to  some  predetermined  code. 

Great  guns  are  now  fired  by  means  of  the  electric  fuse, 
and  this  has  been  found  of  great  value  on  board  ship. 
It  eliminates  the  inaccuracies  of  fire  due  to  the  rolling  of 
the  vessel  during  the  necessary  movement  of  the  arm  in 
pulling  the  usual  lock-string.  The  gun  can  be  discharged 
by  electricity  the  instant  a  good  sight  of  the  object  is 
obtained.  So  also  the  use  of  electricity  allows  of  an 
absolutely  simultaneous  broadside,  which  may  produce 
tremendous  effects  when  several  powerful  guns  are  trained 


OTHER  APPLICATIONS   OF  ELECTRICITY.      347 

upon  a  single  point.  On  board  of  war-vessels,  the  firing 
of  the  guns  is  now  controlled  by  the  captain  from  the 
bridge,  by  means  of  a  so-called  annunciator,  whereby 
either  individual  guns  or  the  entire  battery  may  be  fired 
as  desired.  It  also  shows  at  a  glance  what  guns  are  ready 
for  firing,  and,  by  means  of  a  tell-tale  arrangement,  indi- 
cates to  the  crews  of  the  guns  just  when  the  latter  are 
about  to  be  discharged. 

Heavy  guns  are  now  trained  by  means  of  electro- 
motors ;  and  in  England,  mechanism  of  this  description 
has  been  adapted  to  the  great  cannon  in  the  Spithead 
forts. 

It  is  probable  that  in  the  future,  electricity  will  entirely 
supersede  the  dangerous  and  unreliable  fulminating  sub- 
stances now  used  as  the  means  of  igniting  the  charges  in 
fire-arms.  Tests  have  recently  been  made  with  a  rifle 
fired  by  electricity,  in  which  a  small  primary  galvanic 
battery  is  set  in  the  stock  of  the  gun,  and  connected  with 
the  cartridge,  which  contains  a  fine  wire  which  is  heated 
by  the  passage  of  the  current,  and  in  this  way  the  powder 
is  ignited.  As  it  is  necessary  merely  to  press  a  trigger 
or  button,  to  establish  the  circuit,  this  arrangement  does 
away  with  much  of  the  ordinary  lock  mechanism. 

It  has  been  proposed  to  use  the  gases  generated  by  the 
decomposition  of  water,  as  a  means  of  projecting  shot 
and  shell,  in  lieu  of  gunpowder  or  other  explosive  ;  and 
an  electrolytic  cartridge  has  been  contrived,  which  consists 
simply  of  a  sealed  glass  tube  containing  water,  into  which 
the  ends  of  wires  from  a  battery  enter.  The  water  is 
supposed  to  be  decomposed  by  the  passage  of  the  current, 
and  then  a  spark  passing  between  the  terminals  fires  the 
evolved  gases.  The  practicability  of  this  device  is  by  no 
means  assured. 

The  electric  sight  is  an  ingenious  substitute  for  the  bit 


348  THE  AGE   OF  ELECTRICITY. 

of  white  cotton,  or  other  easily  visible  material,  often  fast- 
ened by  sportsmen  on  the  front  sights  of  their  weapons 
when  hunting  at  night.  It  is  simply  a  thread  of  platinum 
wire  enclosed  in  a  glass  tube,  and  rendered  white  hot  at 
will  by  a  current  from  a  small  galvanic  battery  arranged 
in  the  stock  of  the  piece.  A.  larger  incandescent  lamp 
may  be  arranged  near  the  breech  and  upon  the  barrel,  and 
provided  with  lenses  so  that  its  beam  is  thrown  directly 
upon  the  object  aimed  at. 

Many  very  ingenious  instruments  have  been  devised, 
wherein  electricity  is  employed  for  measuring  the  velocity 
of  projectiles,  by  the  aid  of  which  some  of  the  most  diffi- 
cult problems  in  gunnery  have  been  solved.  One  of  these 
contrivances  registers,  by  means  of  electric  currents  upon 
a  recording  surface  travelling  at  a  uniform  and  very  high 
speed,  the  precise  instant  at  which  a  projectile  passes  cer- 
tain defined  points  in  the  bore  of  the  gun.  Another, 
which  determines  the  initial  velocity  of  projectiles  in  the 
proof  of  gunpowder,  is  capable  of  correctly  measuring 
periods  of  time  as  short  as  -g-o1^  Par^  °f  a  second. 

For  the  explosion  of  mines  or  counter-mines,  in  siege 
operations,  the  electric  fuse  is  now  indispensable.  So, 
also,  submarine  mines,  or  fixed  torpedoes  as  they  are 
termed,  are  not  only  exploded  by  electricity,  but  the  ease 
with  which  the  current  can  be  Controlled  allows  of  their 
being  blown  up  exactly  at  the  moment  when  an  attacking 
vessel  is  in  range.  A  harbor  to  be  protected,  for  exam- 
ple, is  completely  studded  with  these  torpedoes  sunk  out 
of  sight,  but  all  connected  in  electric  circuit  with  certain 
firing-stations  ashore.  By  means  of  lenses,  an  image  of 
the  whole  harbor,  or  all  of  it  within  a  certain  range,  is 
thrown  upon  a  whitened  table  in  a  dark  chamber,  well 
protected  by  bomb-proofs,  so  that  the  progress  of  the 
devoted  ship  is  easily  watched  without  danger  until  she 


OTHER  APPLICATIONS  OF  ELECTRICITY.      349 

has  become  hopelessly  entangled.  The  positions  of  the 
submerged  mines  being  accurately  known,  and  in  fact 
marked  upon  the  whitened  table,  it  simply  remains  to 
watch  the  instant  that  the  image  of  a  vessel  comes  over  a 
marked  point ;  and  then  the  simple  pressure  of  a  key 
transmits  the  current  which  explodes  the  mine.  Friendly 
vessels  may  thus  be  allowed  to  pass  in  safety,  while  hostile 
ships  can  be  promptly  destroyed.  Some  submarine  torpe- 
does are  so  arranged,  that,  when  a  vessel  strikes  them,  a 
weight  is  thrown  across  two  contact  points,  one  of  which 
is  in  connection  with  the  fuse  and  the  other  with  the  bat- 
tery, so  that  the  current  is  thus  led  to  the  fuse,  and  the 
mine  automatically  exploded.  Another  arrangement  is 
such,  that,  when  the  torpedo  is  struck,  the  effect  is  simply 
the  establishment  of  a  weak  current,  not  sufficient  to  blow 
up  the  torpedo,  but  enough  to  make  a  signal  on  shore. 
This  shows  that  the  apparatus  is  in  order,  and  that  the 
exploding  current  can  be  sent  or  not  as  the  shore  operator 
desires.  In  order  to  detect  the  presence  of  fixed  torpe- 
does in  an  enemy's  harbor,  an  instrument  has  been  in- 
vented by  Capt.  McEvoy,  called  the  "torpedo  detector," 
of  which  the  action  is  somewhat  similar  to  that  of  the 
induction  balance  ;  the  iron  of  a  torpedo-case  having  the 
effect  of  increasing  the  number  of  lines  of  force  embraced 
by  one  of  two  opposiuo$boils,  so  that  a  current  induced 
in  one  coil  overpowers  that  induced  in  the  other,  and  a 
distinct  sound  is  heard  in  a  telephone-receiver  in  circuit. 

There  are  two  kinds  of  torpedoes  now  in  use  by  nearly 
all  nations :  namely,  defensive  torpedoes,  which  are  sta- 
tionary, and  are  moored  in  harbors  and  channels ;  and 
offensive  torpedoes,  which  seek  the  enemy's  ship,  and 
either  explode  on  striking  it,  or  are  blown  up  at  the  will 
of  the  controlling  operator  on  shore.  One  of  the  earliest 
suggestions  of  exploding  a  moving  torpedo  by  electricity 


350  THE  AGE   OF  ELECTRICITY. 

was  made  by  Lieutenant  Henry  Moor,  U.S.N.,  who  in 
1846  addressed  a  long  memorial  to  President  Polk,  asking 
for  means  wherewith  to  experiment  upon  his  notion  of 
attaching  electric  wires  to  shells  so  that,  after  these  mis- 
siles had  been  projected,  they  could  be  exploded  whenever 
desired.  The  idea  being  obviously  impracticable  in  the 
form  presented,  it  does  not  appear  that  the  desired  experi- 
ments were  made.  Since  then,  however,  the  idea  has 
been  over  and  over  again  suggested,  of  dropping  torpe- 
does upon  cities  and  fortifications,  from  balloons  sent  aloft 
by  the  besieging  force.  There  is  a  very  fatal  possibility 
in  the  suggestion.  Great  damage  might  be  done  by  letting 
fall  a  "  dejectile  "  anywhere  within  such  a  large  area  of 
populated  country  as  exists  in  and  around  New  York  City, 
for  instance  ;  and  there  seems  to  be  no  practical  reason 
why  a  current  sent  over  a  wire  connected  to  the  balloon 
could  not  easily  control  mechanism  which  would  determine 
the  fall  of  the  torpedo  at  any  desired  instant. 

Without  doubt,  however,  the  most  terribly  effective  and 
dangerous  application  of  electricity  to  war  purposes  is 
that  which  has  now  reached  an  advanced  state  of  devel- 
opment in  the  so-called  fish  torpedo.  The  Sims  electric 
torpedo,  which  has  already  been  adopted  by  the  Govern- 
ment of  the  United  States^  is  a  submarine  boat  with  a 
cylindrical  hull  of  copper,  pointed  at  both  ends,  and  some 
twenty-eight  feet  in  length  by  eighteen  inches  in  diameter. 
This  hull,  in  which  is  placed  the  four  hundred  pounds  of 
explosive  (dynamite)  is  submerged,  and  is  supported  at  a 
certain  depth  by  a  float.  Both  hull  and  float  are  protected 
from  obstructions  by  a  sharp  steel  blade  which  runs  from 
the  bow  of  the  hull  to  the  top  of  the  float,  and  from  the 
stern  of  the  float  to  the  stern  of  the  hull.  The  blade  is 
set  at  such  an  angle  as  to  make  the  torpedo  dive  under  or 
cut  through  any  obstacle.  Within  the  hull  is  an  electro- 


OTHER  APPLICATIONS   OF  ELECTRICITY.      351 

motor  which  drives  the  propelling  screw.  To  this  motor, 
electric  current  is  supplied  by  a  cable  leading  from  a 
dynamo  on  shore,  or  on  the  ship  from  which  the  boat  is 
despatched.  By  means  of  this  current,  the  operator  from 
his  station  on  shore  or  on  shipboard  can  at  will  start,  stop, 
or  steer  the  torpedo,  and  explode  the  charge,  which  can 
also  be  arranged  to  explode  by  contact  of  the  boat  with 
the  attacked  object. 

The  terrible  potency  of  this  weapon  can  hardly  be  over- 
estimated. In  time  of  war  these  deadly  "  fish  "  will  lurk 
in  bomb-proof  canals  adjacent  to  harbors  and  water-ways, 
ready  to  slip  out  the  moment  a  hostile  ship  comes  within 
range  ;  or  they  will  be  anchored  in  different  parts  of  the 
port,  prepared  to  move  on  their  fearful  errand  on  the  pres- 
sure of  a  key.  No  signs  of  them  will  be  visible.  They 
shoot  along  like  huge  sharks  tinder  the  surface  ;  and,  if 
the  water  be  a  little  rough,  nothing  betrays  their  where- 
abouts. The  first  knowledge  an  enemy  has  of  his  peril  is 
the  frightful  explosion  beneath  his  very  feet,  which  hurls 
his  ship  aloft  in  shattered  fragments. 

Conflicts  between  war-vessels,  when  thus  armed,  will  be 
narrowed  down  simply  to  a  question  of  which  vessel  first 
renders  her  torpedo  effective.  Guns  and  armor  will  count 
for  nothing  in  such  a  battle,  which  will  be  more  like  a  duel 
across  a  pocket-handkerchief,  where  the  odds,  slight  as 
they  are,  favor  the  man  who  first  raises  his  pistol  to  cover 
a  vital  point  on  his  adversary.  The  torpedo,  supplied 
with  current  from  the  dynamo  on  board  the  war-ship,  will 
run  ahead  of  its  huge  consort,  and  be  propelled  by  its  own 
power.  Electric  snap  cables  attach  it  to  the  vessel.  The 
enemy  may  be  far  ahead,  but  the  torpedo  can  travel  at  the 
rate  of  eleven  mile's  an  hour.  The  attacking  vessel  waits 
only  to  get  within  a  mile  or  so  of  her  adversary,  and  then 
she  ulets  slip  the"  fish  "of  war."  The  operator  on 


352  THE  AGE   OF  ELECTRICITY. 

board  ship  watches  the  two  little  balls  which  are  fastened 
above  the  float,  just  visible  above  the  waves, — visible, 
however,  only  when  one  knows  where  to  look  for  them,  — 
and  has  a  good  glass  handy.  He  keeps  these  balls  in 
line;  this  enables  him  to  see  where  the  "fish"  is  going, 
and  a  touch  on  a  button  steers  the  torpedo  in  either  direc- 
tion. The  enemy,  anticipating  perhaps  some  such  attack, 
encompasses  himself  with  floating  booms.  No  matter  :  the 
fish  goes  under  them.  Suddenly  a  galvanometer-needle, 
which  the  operator  is  intently  watching,  moves :  the 
"fish"  thus  signals  back  word  that  it  has  met  its  prey. 
The  exploding  button  is  pressed.  A  column  of  spray 


Fig.  141. 


leaps  into  the  air  ;  a  dull  explosion  is  heard  ;  a  great  black 
monster  rolls  over  on  its  side,  and  then  the  waves  break 
above  the  huge  iron-clad  and  its  crew  of  hundreds  of  souls. 
Fig.  141  represents  the  "fish."  The  electric  cable  is 
shown  passing  into  the  lower  portion  of  its  submerged 
hull ;  and  at  the  stern  is  the  propelling-screw  which  is 
protected  by  a  guard-ring  from  chance  entanglement  with 
ropes,  nets,  or  other  obstructions.  The  rudder  is  on  the 
upper  part  of  the  hull,  just  forward  of  the  screw.  In 
order  to  show  just  what  this  apparatus  has  actually  done, 
we  append  (Fig.  142)  a  facsimile  of  a  chart  of  an  experi- 
mental trial  made  by  General  Abbot,  U.S.A.,  at  the 
Willet's  Point  torpedo-station.  Here  the  course  of  the 
fish  as  it  was  guided  from  the  shore  is  accurately  plotted, 


OTHER  APPLICATIONS  OF  ELECTRICITY.      353 

so  as  to  show  all  its  windings.  Note  the  curve  on  the 
left,  indicating  the  doublings  of  the  torpedo  in  its  sinuous 
course,  as  if  it  were  chasing  some  victim  vainly  attempt- 
ing in  this  way  to  escape  ;  and  note  also  how  it  can  be 
sent  out  to  run  two  or  three  thousand  feet,  and  then 
caused  to  return  like  a  falcon  to  the  hand  of  its  control- 
ler. Even  if  an  enemy  does  sight  the  partly  submerged 


Fig.  142. 

float,  it  will  do  him  no  good  to  fire  at  it.  It  is  filled  with 
cork  or  like  light  material,  and  more  than  half  of  it  might 
be  torn  away  without  much  impairing  its  buoyancy. 

How  to  defend  against  a  torpedo  of  this  sort,  is  an  un- 
solved problem.  Heavy  nettings  around  a  vessel  might 
stop  one  fish  ;  but  if  the  immediate  explosion  did  not  sink 
the  ship  itself,  it  would  tear  the  netting,  however  strong, 
to  pieces,  and  there  would  be  an  open  way  for  another 


354  THE  AGE   OF  ELECTRICITY. 

fish,  sent  immediately  on  the  heels  of  the  first.  The 
telephone  bids  fair  to  be  a  good  means  of  detecting  the 
approach  of  a  submarine  torpedo ;  for,  if  one  of  its  ter- 
minal wires  is  connected  with  a  submerged  plate,  the 
sound  of  the  rapidly  approaching  fish  can  easily  be  heard. 
This  would  be  of  little  avail,  however,  unless  some  sort 
of  dredging-craft  could  run  quickly  in  behind  the  fish,  and 
cut  the  electric  cable  ;  but  in  the  time  which  it  would  take 
to  recognize  the  approaching  danger,  and  to  notify  the 
cutting  vessel,  —  supposing  the  latter  to  be  in  perfect 
readiness,  —  the  torpedo  would  probably  get  alongside 
and  do  its  work.  The  problem  is  one  of  great  impor- 
tance, and  many  inventors  are  hard  at  work  upon  it. 

Military  telegraphs  are  now  indispensable  to  armies  in 
the  field.  Miles  of  wire  are  carried  on  reels,  in  specially 
constructed  wagons,  which  hold  also  batteries  and  instru- 
ments. Some  of  the  wire  is  insulated  so  that  it  can  rest 
on  the  ground,  and  thus  be  laid  out  with  great  speed ; 
while  other  wire  is  bare,  and  is  intended  to  be  strung  up 
wherever  conveniently  possible.  For  mountain  service, 
the  wires  and  implements  are  carried  by  pack-animals ; 
and  often,  for  reconnoitring,  reels  of  wire  are  carried 
like  knapsacks  on  the  backs  of  the  men.  All  modern 
armies  now  have  a  regularly  drilled  telegraph-corps  ;  and 
telegraphic  communication  is  constantly  maintained  be- 
tween an  advance-guard  and  the  main  body  of  an  army, 
or  between  different  divisions  or  brigades  on  the  field. 
During  the  English  operations  in  Egypt,  the  advance- 
guard  was  not  only  kept  in  communication  with  head- 
quarters, but  with  England  ;  so  that,  after  the  battle  of 
Tel-el  Kebir,  news  of  the  victory  was  telegraphed  to  the 
Queen,  and  her  answer  received,  within  forty-five  minutes. 

The  telephone  in  its  various  forms  is  also  of  great  mili- 
tary value.  It  enables  constant  communication  to  be  held 


OTHER  APPLICATIONS   OF  ELECTRICITY.      355 

between  pickets,  skirmish-lines,  scouting  parties,  and  the 
officer  in  general  command.  It  has  been  proposed  to 
bury  sensitive  microphones  in  the  earth  along  roads, 
around  forts  and  camps,  so  that  the  approach  or  move- 
ments of  a  hostile  force  could  instantly  be  detected. 
Actual  experiment  has  proved  that  a  delicate  apparatus  of 
this  sort  will  render  audible  the  sound  of  a  spade  scraping 
upon  the  earth,  when  digging  is  going  on  some  five  hun- 
dred feet  away  from  the  buried  instrument ;  and  the  foot- 
falls of  men  and  horses,  and  the  rumble  of  wheels,  occur- 
ring at  even  greater  distances,  can  easily  be  recognized. 

The  most  noted  of  the  early  experiments  in  electrical 
blasting  was  the  destruction  of  the  submerged  hull  of  the 
ill-fated  "Royal  George "  man-of-war,  in  1840.  The  most 
famous  of  recent  electrical  blasts  was  the  destruction  of 
Flood  Rock  in  the  East  River,  near  New- York  City,  in  the 
fall  of  1885.  Some  idea  of  the  immensity  of  this  work 
may  be  derived  from  the  fact  that  the  total  area  under- 
mined was  over  nine  acres,  and  that  21,670  feet  of  galleries 
honeycombed  the  solid  rock.  In  the  roof  and  tops  of  the 
piers  left  to  support  it,  over  thirteen  thousand  holes  were 
made.  The  explosives  used  were  dynamite  and  rack-a-rock, 
a  mixture  of  chlorate  of  potash  and  di-nitro-benzole.  Into 
each  dynamite  cartridge,  an  electric  fuse  was  placed,  filled 
with  fulminate  of  mercury,  and  containing  a  small  platinum 
bridge,  which,  when  the  current  passes,  is  heated  to  red- 
ness, and  the  fulminate  thus  exploded.  The  entire  mine 
was  divided  into  twenty-four  independent  circuits,  each 
circuit  representing  or  covering  a  certain  section.  Within 
each  circuit  were  twenty-five  fuses  or  mine-exploders. 
Each  of  the  twenty-four  circuits  had  its  own  wire,  and  the 
like  ends  of  all  the  wires  were  brought  together ;  the  posi- 
tive ends,  for  example,  being  dipped  into  one  cup  of  mer- 


356  THE  AGE  OF  ELECTRICITY. 

cury,  and  the  negative  ends  into  another  and  a  separate 
cup.  It  was  simply  necessary  to  unite  the  two  cups  of 
mercury  by  a  single  wire  in  circuit  with  a  battery,  to  send 
a  current  through  all  the  circuits  simultaneously.  The 
cartridges  in  the  drill-holes  were  not  electrically  connected, 
nor  were  any  fuses  arranged  in  them.  The  current  simply 
exploded  the  six  hundred  "  mine-exploders  "  distributed 
through  the  galleries  ;  and  the  forty  thousand  cartridges, 
containing  seventy-five  thousand  pounds  of  dynamite  and 
two  hundred  and  forty  thousand  pounds  of  rack-a-rock, 
detonated  "  by  sympathy." 

For  marine  use,  electric  lights  are  employed  for  the 
running  lights  of  vessels.  Electric  telegraphs  are  utilized 
to  signal  directions  from  the  bridges  of  steamers  to  the 
engine-room  and  helm ;  and  numerous  devices  have  been 
contrived,  whereby  the  compass-needle  in  moving  is  caused 
to  control  an  electric  circuit  which  through  suitable  mechan- 
ism governs  the  rudder,  so  that  a  vessel  can  be  made  to 
steer  herself  upon  any  given  course.  Various  forms  of 
electric  logs  have  been  invented,  which  provide  for  a  con- 
tinuous registration,  on  board  the  ship,  of  the  actual  dis- 
tance travelled  through  the  water.  The  great  English 
iron-clad  "Colossus"  was  launched  by  the  aid  of  elec- 
tricity ;  a  weight,  which  in  falling  removed  the  dog-shores, 
being  controlled  by  a  large  electro-magnet,  so  that  at  the 
proper  moment  the  simple  pressure  of  a  button  allowed  the 
huge  craft  to  move  freely  into  the  water.  The  propulsion 
of  small  vessels  by  electro-motors  has  already  been  referred 
to.  It  is  probable  that  these  engines  will  come  into  more 
and  more  extended  use  afloat  for  the  hoisting  and  bracing 
of  yards,  the  lifting  of  heavy  weights,  and  other  work,  for 
which  manual  labor  on  sailing-vessels,  or  steam  on  steam- 
ships, is  now  employed. 


OTHER  APPLICATIONS   OF  ELECTRICITY.      357 

For  any  one  who  has  been  to  sea,  it  is  not  hard  to  real- 
ize the  terrible  odds  against  any  unfortunate  who  falls  into 
the  black  darkness  of  the  waves  at  night  from  the  rigging 
of  a  fast  vessel.  The  ship  may  leave  the  swimmer  a  mile 
or  more  astern  before  her  speed  can  even  be  checked  ;  and 
to  reverse  her  course  involves  sweeping  around  a  circle 
miles  in  length.  And  then  how  is  the  man  to  be  found, 
amid  the  multitudinous  and  ever-changing  hills  and  val- 
leys of  the  waves  ?  Here,  however,  the  electric  light  has 
proved  of  splendid  utility.  A  British  man-of-war  recently 
was  steaming  at  moderate  speed  one  very  dark  night,  when 
suddenly  the  always  appalling  cry  of  "  Man  overboard  !  " 
was  raised.  Two  of  the  officers,  who  had  seen  the  sailor 
fall  from  the  rigging,  heroically  leaped  into  the  water  to 
his  rescue.  Almost  instantly  the  electric  light  on  the  lofty 
deck  flashed  out  its  great  beam,  revealing  the  three  men 
clinging  to  a  life-buoy.  As  the  ship  lost  her  way,  and 
then  came  about,  the  brilliant  ray  followed  them  ;  and  so, 
when  the  life-boat  was  lowered,  it  was  simply  necessary  to 
steer  in  the  path  of  the  beam  to  reach  the  buoy.  In  six 
minutes  after  the  alarm  was  given,  the  men  were  saved, 
the  boat  hoisted,  and  the  ship  once  more  on  her  course. 

Among  the  more  important  applications  of  electricity 
to  railway  purposes,  is  that  of  working  automatic  signals, 
which  guard  the  road,  and  give  warning  of  danger,  with- 
out the  intervention  of  man.  It  is  a  requisite  of  any 
signal-system,  that  the  normal  condition  of  its  signals 
should  indicate  danger ;  so  that  in  case  of  any  derange- 
ment of  apparatus,  accidental  or  intentional,  warning  will 
be  given.  Thus  failure  to  act  will  at  most  stop  or  check 
the  movement  of  a  train.  In  Hall's  system,  an  open  cir- 
cuit is  employed,  and  the  current  which  keeps  the  signals 
set  at  "  safety  "  is  transmitted  over  wires.  This  current 


358  THE  AGE  OF  ELECTRICITY. 

being  broken  by  an  engine  entering  a  block-section,  and 
touching  a  circuit-closer,  sets  the  signal  at  "danger.'* 
The  so-called  Union  system  uses  a  closed  circuit,  with  an 
electric  current  moving  through  the  rails.  When  a  section 
of  road  is  guarded  by  this  device,  the  entrance  of  a  loco- 
motive breaks  the  current  simply  by  placing  its  wheels 
upon  the  conducting  rails,  and  thereupon  visible  signals  of 
danger  are  given  ;  and  when  a  train  approaches  a  station 
or  crossing,  a  warning  bell  is  rung.  To  electric  railways 
and  railway  telegraphs,  reference  has  already  been  made. 
The  electric  lighting  of  railway-trains  is  now  accom- 
plished by  the  aid  of  storage-batteries  and  incandescent 
lamps  ;  the  batteries  being  supplied  by  a  small  dynamo 
carried  on  the  locomotive.  Electric  brakes,  which  depend 
upon  the  attractive  energy  of  electro-magnets  being  ex- 
erted to  press  the  "shoes"  against  the  wheels,  are  used 
on  some  European  railways. 

The  earliest  application  of  electricity  to  music  was  prob- 
ably that  made  by  Pere  Laborde  in  1755,  in  his  so-called 
clavecin  electrique.  This  curious  instrument  is  described 
in  Sigaud  de  la  Fond's  treatise  of  1767,  as  follows  :  "A 
bar  of  iron  insulated  on  a  silken  cord  carries  bells  of  differ- 
ent sizes  for  the  different  notes,  two  bells  being  supplied 
for  each  note.  One  of  the  two  bells  is  suspended  by  a 
brass  wire,  the  other  by  a  thread  of  silk.  The  hammer, 
held  by  a  silken  cord,  hangs  between  the  two.  From  the 
bell  suspended  by  the  silk,  extends  a  brass  wire,  the  end 
of  which  is  fastened  by  a  second  cord,  and  terminates  in 
a  ring  which  receives  a  small  iron  lever,  which  rests  on 
an  insulated  iron  bar.  By  this  arrangement  the  bell  sus- 
pended by  the  brass  wire  is  electrified  from  the  iron  bar 
which  carries  it ;  and  the  other,  which  is  hung  from  this 
bar  by  the  silk  thread,  is  electrified  by  the  other  iron  bar, 


OTHER  APPLICATIONS   OF  ELECTRICITY.      359 

on  which  the  lever  rests.  When  a  key  is  pressed  down, 
the  lever  is  raised,  and  caused  to  touch  the  non-insulated 
bar.  At  the  same  instant  the  hammer  is  set  in  motion, 
and  strikes  the  two  bells  with  such  rapidity  that  a  single 
undulating  [si'c]  sound  is  produced,  which  imitates  very 
closely  the  tremolo  effect  of  the  organ.  As  soon  as  the 
lever  falls  on  the  electrified  rod,  the  hammer  stops.  Thus 
each  key  controls  a  lever,  and  each  lever  a  pair  of  bells  ; 
and  in  this  way  airs  may  be  played  as  on  any  other 
clavecin." 

The  idea  of  controlling  the  hammers  of  a  piano  by 
electro-magnets,  which  should  be  energized  and  de-ener- 
gized from  a  distant  station,  was  suggested  several  years 
ago  ;  and  a  glowing  prospectus  was  issued  by  an  electro- 
musical  company  which  proposed  to  play  any  one's  piano 
—  after  a  few  alterations  in  its  inner  mechanism  —  by 
electricity.  There  was  to  be  a  central  station,  in  which 
was  to  be  located  the  single  controlling  keyboard  which 
governed  all  the  pianos  of  the  various  subscribers ;  and 
here  noted  artists  were  to  play  between  stated  hours. 
When  any  subscriber  desired  music  in  his  parlor,  he  had 
only  to  consult  the  programme,  distributed  daily,  to  learn 
what  morceau  was  in  process  of  performance,  and  then 
turn  his  switch,  when  his  piano  would  instantly  begin  ;  so 
that  in  the  humblest  dwelling  the  choicest  productions  of 
the  great  masters,  executed  by  the  Von  Bulows  and  the 
Liszts  and  the  Rubinsteins  of  the  day,  were  to  be  as  read- 
ily available  and  as  familiar  as  the  "Maiden's  Prayer" 
and  "Monastery  Bells."  Of  course  there  were  some 
obvious  difficulties  attending  this  scheme ;  such,  for  ex- 
ample, as  that  of  the  possibility  of  receiving  the  wrong 
tunes, — the  "Dead  March  in  Saul,"  for  example,  at  a 
dancing-party,  or  the  last  minstrel  ditty  at  a  funeral :  but 
the  addition  of  an  electric  annunciator  which  would  auto- 


360  THE  AGE  OF  ELECTRICITY. 

matically  exhibit  the  name  of  the  piece,  it  was  believed, 
would  prevent  this  trouble.  So  far  as  is  known,  the  plan 
never  went  into  practical  effect,  although  some  electro- 
musical  concerts  were  given,  in  which  half  a  dozen  pianos 
were  played  in  unison,  making  much  noise  but  little  music. 
In  the  explosive  concert-performances,  such  as  delight  the 
ears  of  the  throngs  at  Coney  Island  and  other  popular 
resorts,  electricity  is  an  indispensable  assistant.  To  Mr. 
Patrick  Gilmore  is  probably  due  the  credit  of  discharging 
a  whole  battery  of  cannon  in  strict  accentuation,  with  the 
"Anvil  Chorus,"  by  means  of  electric  fuses  and  wires 
leading  from  the  conductor's  desk ;  the  effect  being,  both 
metaphorically  and  literally,  "stunning." 

The  harmonic  telegraph,  whereby  musical  sounds  can 
be  transmitted  between  distant  points,  has  already  been 
explained.  Electric  organs  have  been  constructed,  in 
which  the  action  and  stops  are  entirely  controlled  by  the 
closing  of  circuits  by  the  keys,  etc.  In  Grace  Church, 
New  York,  the  chancel  organ  is  placed  in  a  chamber  built 
for  the  purpose  at  the  angle  formed  by  the  east  wall  of 
the  south  transept  and  the  chancel  wall.  The  gallery 
organ  stands  at  the  west  end  of  the  church,  over  the  main 
entrance.  The  echo  organ  is  situated  on  the  roof,  over 
the  intersection  of  nave  and  transept.  These  organs  are 
connected  with  the  keyboards  in  the  chancel,  and  are  thus 
under  the  complete  control  of  one  performer.  A  curious 
contrivance,  called  a  melograph,  has  been  devised  by  Mr. 
Carpenter,  which  both  registers  and  reproduces  music. 
The  operator  manipulates  keys  like  those  of  a  piano, 
which  control  currents  which  operate  perforators  in  an 
endless  strip  of  paper,  cutting  long  or  short  slits  accord- 
ing to  the  duration  of  the  note  struck.  This  paper  pro- 
ceeds to  a  second  apparatus,  where  circuit  is  made  only 
through  the  openings  in  the  paper  strip,  and  thus  only  cer- 


OTHER  APPLICATIONS  OF  ELECTRICITY.      361 

tain  reeds  are  set  in  operation,  to  reproduce  the  original 
melody.  An  electrical  recording  device  has  also  been 
invented,  designed  to  rescue  the  fugitive  improvisations  of 
musical  genuises  from  oblivion.  Whenever  a  key  is  struck, 
a  note  is  marked  telegraphically  on  a  moving  strip  of 
paper. 

Possibly  the  reader,  while  seated  in  a  theatre  or  opera- 
house,  and  waiting  for  the  curtain  to  rise,  has  devoted  a  few 
minutes  to  wondering  how  the  innumerable  burners  of  the 
great  chandelier  which  hangs  from  the  dome  are  lighted ; 
or  how,  even  by  the  longest  of  poles,  a  match  can  be  car- 
ried to  gas-jets  located  apparently  in  the  most  inaccessible 
places.  Then  suddenly  there  is  a  succession  of  sharp 
cracks  ;  and,  before  one's  eyelids  can  rise  after  the  in- 
voluntary wink,  every  burner  is  aflame.  This  is  electrical 
gas-lighting.  Electricity  is  a  generous  rival.  Perhaps 
because  of  the  inapproachable  superiority  of  its  own  light, 
it  can  afford  to  help  its  weaker  antagonist.  Closer  or 
nearer  inspection  of  the  myriad  gas-burners  of  a  theatre 
will  show  that  they  are  all  connected  by  delicate  wires, 
and  that  at  the  tip  of  every  one  of  them  are  a  couple  of 
metal  points,  between  which  the  circuit  is  interrupted. 
Now,  when  a  powerful  electric  current  is  sent  into  the 
wire,  it  travels  over  the  conductor  until  it  reaches  one  of 
these  breaks,  over  which  it  jumps  from  point  to  point ; 
and  in  its  leap  a  spark  appears.  The  gas  is  first  turned 
on  to  all  the  burners.  No  matter  how  many  they  may  be, 
the  passage  of  the  current  is  so  infinitely  swift  that  the 
spark  at  the  tip  of  every  one  of  them  is  made  at  the  same 
instant,  and  every  outgoing  stream  of  gas  is  thus  ignited 
at  once.  This  is  a  very  old  invention.  It  appears  to 
have  been  first  made  public  by  one  Joseph  Beck,  in  an 
English  scientific  paper,  in  1839.  At  the  same  time  it  is 


362  THE  AGE   OF  ELECTRICITY. 

perhaps  the  simplest,  as  well  as  most  commonly  used, 
arrangement  of  electrical  gas-lighting  apparatus.  There 
are  many  more  modern  contrivances  for  the  same  purpose, 
which  display  exceptional  ingenuity.  For  example,  there 
are  several  forms  of  so-called  automatic  lighters,  which  on 
the  first  pressure  of  a  button,  no  matter  how  far  distant 
from  the  burner,  a  communicating  wire  being  present,  not 
only  light  the  gas,  but  before  doing  so  turn  it  on.  Then, 
on  a  second  pressure  of  the  same  button,  the  gas  is  turned 
off.  This  has  been  applied  to  street-lights,  so  that  all  the 
gas-lamps  in  a  large  district  can  thus  be  automatically 
lighted  and  extinguished  without  any  help  from  the  tradi- 
tional lamp-lighter  and  his  ladder.  Then  there  are  simple 
little  contrivances  connected  to  individual  burners,  so  that 
it  is  necessary  simply  to  pull  down  a  hanging  wire,  or 
merely  to  turn  on  the  gas  by  the  cock  in  the  ordinary  way, 
when  a  little  spring  is  wiped  past  a  metal  point  on  the 
burner-tip,  a  spark  made,  and  the  gas  lighted.  Of  course 
it  is  a  great  convenience,  on  going  into  a  dark  room,  to 
be  saved  the  hunt  for  fugitive  matches,  and  to  have  noth- 
ing to  do  but  find  the  fixture,  and  turn  on  the  gas  ;  and  it 
is  even  a  greater  comfort  for  paterfamilias  to  know  that 
when  strange  noises  in  the  lower  part  of  the  house  arouse 
him  in  the  middle  of  the  night,  he  has  not  to  descend  into 
the  darkness  to  meet  an  unknown  fate,  but  simply  to  touch 
a  button  by  his  bedside,  when  every  burner  in  every  room, 
if  he  so  desires,  will  blaze,  and  render  his  further  investiga- 
tion —  whether  it  be  for  cats  or  burglars  —  at  least  free 
from  nameless  fears  of  an  unseen  and  hence  mysterious 
intruder. 

The  number  of  varieties  of  electric  alarms,  indicators, 
and  annunciators,  is  simply  legion.  Most  of  them  are 
automatic  in  their  action.  Others  —  like  the  hotel  annun- 


OTHER  APPLICATIONS   OF  ELECTRICITY.      363 

ciators,  which,  when  a  button  is  pressed  in  a  room,  cause 
a  bell  to  sound  in  the  office,  and  reveal  the  number  of  the 
apartment  whence  the  signal  comes  —  require  a  closing  or 
breaking  of  the  circuit  by  hand.  The  mechanism  of  all 
of  these  contrivances  embodies  an  electro-magnet,  which, 
when  the  current  is  established  by  pressing  the  button, 
attracts  a  metal  shutter  bearing  the  number,  and  thus 
moves  it  so  that  the  number  becomes  visible  through  an 
opening  in  a  screen  ;  or  else  the  magnet  acts  to  release  a 
catch  so  that  the  shutter  is  allowed  to  fall  into  view.  The 
automatic  contrivances  either  simply  give  an  alarm  as  by 
ringing  a  bell  or  exhibiting  a  signal,  or  else  actually  control 
the  power  of  some  contrivance  which  does  certain  work. 
Sometimes  an  alarm  is  given,  and  mechanism  operated  at 
the  same  time.  Thus  electrical  low- water  regulators  have 
been  devised  for  steam  boilers,  which,  when  the  water 
falls  below  a  certain  level,  turn  on  the  steam  to  sound  the 
whistle,  and  also  open  the  feed  valve  to  let  in  a  supply  of 
water.  Other  electrical  regulators  have  been  arranged  in 
connection  with  the  dampers  of  furnaces,  to  open  and 
close  them  at  the  proper  time.  So  also,  in  connection 
with  steam-engines,  electrical  governors  have  been  adopted, 
which  control  the  slide-valves  and  the  admission  of  steam. 
Nearly  all  the  electrical  heat-regulators  depend  upon  the 
elongation  or  contraction  of  a  so-called  thermostatic  bar, 
made  of  metals  very  sensitive  to  differences  in  temper- 
ature ;  or  upon  the  movement  of  the  mercury  in  a  ther- 
mometer-tube. When  the  heat  of  an  apartment  exceeds  a 
certain  limit,  the  bar  expands,  or  the  mercury  in  the  ther- 
mometer rises,  and  establishes  a  circuit,  through  which 
the  current,  being  free  to  pass,  actuates  mechanism  for 
opening  a  ventilator  or  damper,  and  so  letting  cool  air  into 
and  hot  air  out  of  the  chamber.  This  idea  has  been  very 
successfully  applied  to  artificial  incubators,  in  which  it  is 


364 


THE  AGE  OF  ELECTRICITY. 


necessary  to  maintain  a  temperature  of  about  102°  Fah. 
very  uniformly  during  the  long  incubating  period.  One 
contrivance  of  this  class  is  arranged  to  regulate  the 
temperature  of  an  incubator  heated  by  hot  water  from  a 
small  boiler,  with  great  accuracy.  The  damper  opens  and 
shuts  responsive  to  even  a  fraction  of  a  degree  difference 
in  temperature,  and  the  proportion  of  eggs  hatched  — often 
as  high  as  eighty-two  per  cent  —  shows  how  perfectly  the 
sentinel  current  does  its  work. 

In  some  cases  the  body  to  be  expanded  by  heat  is  made 


Fig.  143. 

in  the  form  of  a  spring  as  at  S,  in  Fig.  143.  When  the 
temperature  rises,  the  end  of  the  spring  makes  contact 
with  the  point  P,  and  thus  establishes  the  electrical  circuit 
from  one  wire  to  another. 

Burglar-alarms  are  now  in  every-day  use.  Some  of 
them  depend  upon  the  bringing  into  contact  of  two  pieces 
of  metal  by  the  opening  of  a  door  or  window,  thus  estab- 
lishing the  circuit  from  a  battery  to  an  alarm-bell  and 
to  an  annunciator  showing  the  location  of  the  place  of 
attempted  entry.  Others  depend  upon  the  breaking  of  a 
closed  circuit,  releasing  some  form  of  alarm.  Others  are 
especially  adapted  to  safes,  so  that  in  event  of  a  burglar 
breaking  in,  or  even  tampering  with  the  receptacle,  the 


OTHEE  APPLICATIONS  OF  ELECTRICITY.      365 

alarm  is  caused  to  sound.  Door-mats  and  matting  are 
also  constructed  with  contact  plates  brought  together  by 
the  pressure  of  the  foot  of  a  person  stepping  on  them, 
and  thus  establishing  a  current  to  a  bell  which  thus  gives 
warning  of  any  one  entering  or  moving  about  a  protected 
room.  In  large  cities  where  district  telegraph  companies 
are  in  existence,  arrangements  are  made  whereby  all  the 
doors  and  windows  of  a  residence  can  be  connected  with 
an  alarm  at  a  central  station ;  so  that  the  occupant  can 
leave  the  house  untenanted,  with  confidence  that  any  bur- 
glar attempting  to  enter  will  at  the  same  time,  and  indeed 
without  his  own  knowledge,  signal  his  own  proceedings  to 
the  station,  whence  a  policeman  will  be  sent  after  him  long 
before  he  can  do  any  mischief. 

In  brief,  there  are  almost  as  many  alarms,  regulators, 
and  indicators,  as  there  are  special  circumstances  needing 
them.  One  of  the  most  ingenious  contrivers  of  appara- 
tus of  this  sort  was  the  famous  French  conjuror  Robert 
Houdin,  who  retired,  after  his  eventful  career,  to  a  charm- 
ing mansion  called  the  "Priory,"  in  the  village  of  St. 
Gervais.  There  he  amused  himself  by  devising  a  variety 
of  ingenious  electrical  contrivances,  many  of  which  are 
graphically  described  in  the  following  extract  published 
several  years  ago  :  — 

"  The  main  entrance  to  the  Priory  is  a  carriage-way  closed  by  a 
gate.  Upon  the  left  of  this  is  a  door  for  the  admission  of  visitors 
on  foot :  on  the  right  is  placed  a  letter-box.  The  mansion  is  sit- 
uated a  quarter  of  a  mile  distant,  and  is  approached  by  a  broad  and 
winding  road  well  shaded  with  trees. 

"  The  visitor  presenting  himself  before  the  door  on  the  left  sees 
a  gilt  plate  bearing  the  name  of  Robert  Houdin,  below  which  is 
a  small  gilt  knocker.  He  raises  this  according  to  his  fancy;  but, 
no  matter  how  feeble  the  blow,  a  delicately  tuned  chime  of  bells 
sounding  through  the  mansion  announces  his  presence.  When 
the  attendant  touches  a  button  placed  in  the  hall,  the  chime  ceases, 


366  THE  AGE  OF  ELECTRICITY. 

the  bolt  at  the  entrance  is  thrown  back,  the  name  of  Robert  Hou- 
din  disappears  from  the  door,  and  in  its  place  appears  the  word 
*  entrez '  in  white  enamel.  The  visitor  pushes  open  the  door,  and 
enters  ;  it  closes  with  a  spring  behind  him,  and  he  cannot  depart 
without  permission. 

"  This  door  in  opening  sounds  two  distinct  chimes,  which  are 
repeated  in  the  inverse  order  in  closing.  Four  distinct  sounds 
then,  separated  by  equal  intervals,  are  produced.  In  this  way  a 
single  visitor  is  announced.  If  many  come  together,  as  each  holds 
the  door  open  for  the  next  the  intervals  between  the  first  two  and 
the  last  two  strokes  indicate  with  great  accuracy,  especially  to  a 
practised  ear,  the  number  who  have  entered  ;  and  the  preparation 
for  the  reception  is  made  accordingly.  A  resident  of  the  place  is 
readily  distinguished  ;  for,  knowing  in  advance  what  is  to  occur, 
he  knocks,  and  at  the  instant  when  the  bolt  slips  back  he  enters. 
The  equidistant  strokes  follow  immediately  the  pressing  of  the 
button.  But  a  new  visitor,  surprised  at  the  appearance  of  the 
word  'entrez,'  hesitates  a  second  or  two,  then  presses  open  the  door 
gradually,  and  enters  slowly.  The  four  strokes,  now  separated  by 
a  short  interval,  succeed  the  pressing  of  the  button  by  quite  an 
appreciable  time  ;  and  the  host  makes  ready  to  receive  a  stranger. 
The  travelling  beggar,  fearful  of  committing  some  indiscretion, 
raises  timidly  the  knocker;  he  hesitates  to  enter,  and  when  he  does 
it  is  only  with  great  slowness  and  caution.  This  the  chimes  un- 
erringly announce.  It  seems  to  persons  at  the  house  as  if  they 
actually  saw  the  poor  mendicant  pass  the  entrance;  and  in  going 
to  meet  him  they  are  never  mistaken. 

"When  a  carriage  arrives  at  the  Priory,  the  driver  descends 
from  his  box,  enters  the  door  by  the  method  now  described,  and  is 
directed  to  the  key  of  the  gate  by  a  suitable  inscription.  He  un- 
locks the  gate,  and  swings  open  its  two  parts;  the  movement  is 
announced  at  the  house,  and  on  a  table  in  the  hall  bearing  the 

words,  'The  gate  is ,'  appears  the  word  'open'  or  'closed,' 

according  to  the  fact. 

"The  letter-box,  too,  has  an  electric  communication  with  the 
house.  The  carrier,  previously  instructed,  drops  in  first  all  the 
printed  matter  together;  then  he  adds  the  letters  one  by  one.  Each 
addition  sounds  the  chimes ;  and  the  owner,  even  if  he  has  not  yet 
risen,  is  apprised  of  the  character  of  his  despatches.  To  avoid 
sending  letters  to  the  village,  they  are  written  in  the  evening;  and 
a  commutator  is  so  arranged,  that,  when  the  carrier  drops  the  mail 


OTHER  APPLICATIONS  OF  ELECTRICITY.      367 

into  the  box  the  next  morning,  the  electricity,  in  place  of  sound- 
ing the  chimes  in  the  house,  sounds  one  over  his  head.  Thus 
warned,  he  comes  up  to  the  house  to  leave  what  he  has  brought, 
and  to  take  away  the  letters  ready  for  mailing. 

"  '  My  electric  doorkeeper  then  [says  Houdin]  leaves  me  nothing 
to  be  desired.  His  service  is  most  exact;  his  fidelity  is  thoroughly 
proven;  his  discretion  is  unequalled;  and  as  to  his  salary,  I  doubt 
the  possibility  of  obtaining  an  equal  service  for  a  smaller  remuner- 
ation.' 

"  M.  Houdin  possesses  a  young  mare  whom  he  has  named 
Fanchette.  To  this  animal  he  is  much  attached,  and  cares  for  her 
with  the  greatest  assiduity.  A  former  hostler,  who  was  an  active, 
intelligent  man,  had  become  devoted  to  the  art  so  successfully  prac- 
tised by  his  employer  in  previous  years.  His  knowledge,  however, 
was  confined  to  a  single  trick;  but  this  he  executed  with  rare  abil- 
ity. This  trick  consisted  in  changing  the  oats  of  his  master  into 
five-franc  pieces.  To  prevent  this  peculation,  the  stable,  distant 
from  the  house  seven  or  eight  rods,  is  connected  with  it  by  elec- 
tricity so  that  by  means  of  a  clock  fixed  in  the  study  the  necessary 
quantity  of  food  is  supplied  to  the  horse,  at  a  fixed  hour,  three 
times  a  day.  The  distributing  apparatus  is  very  simple,  consisting 
of  a  square  box,  funnel-shaped,  which  discharges  the  oats  in  the 
proportion  previously  regulated.  Since  the  oats  are  allowed  to  fall 
only  when  the  stable-door  is  locked,  the  hostler  cannot  remove 
them  after  they  are  supplied;  nor  can  he  shut  himself  in  the  sta- 
ble, and  thus  get  the  oats,  as  the  door  locks  only  upon  the  outside. 
Moreover  he  cannot  re-enter,  and  abstract  them,  because  an  alarm 
is  caused  to  sound  in  the  house  if  the  door  be  open  before  the  oats 
are  consumed. 

''This  study  clock  transmits  the  time  to  two  dial-plates.  One, 
placed  upon  the  front  of  the  house,  gives  the  hour  of  the  day  to 
the  neighborhood;  the  other,  fastened  to  the  gardener's  lodge  facing 
the  house,  gives  the  time  to  its  inmates.  Several  smaller  dials, 
operated  similarly,  are  placed  in  various  apartments.  They  all, 
however,  have  but  a  single  striking  part;  but  this  is  powerful 
enough  to  be  heard  over  the  entire  village.  Upon  the  top  of  the 
house  is  a  tower  containing  a  bell  on  which  the  hours  of  meals  are 
announced.  Below  this  is  a  train  of  wheel-work  to  raise  the  ham- 
mer. To  avoid  the  necessity  of  winding  up  the  weight  every  day, 
an  automatic  arrangement  is  employed  which  utilizes  a  force  ordi- 
narily lost.  Between  the  kitchen,  situated  upon  the  ground-floor, 


368  THE  AGE  OF  ELECTRICITY. 

and  the  clock-work  in  the  garret,  there  is  a  contrivance  so  arranged 
that  the  servants  in  going  to  and  fro  about  their  work  wind  up  the 
weight  without  being  conscious  of  it.  An  electric  current,  set  in 
motion  by  the  study  regulator,  raises  the  detent,  and  permits  the 
number  of  strokes  indicated  by  the  dial.  The  manner  of  distrib- 
uting the  time  from  the  study,  Houdin  finds  very  useful.  When, 
for  any  reason,  he  wishes  the  meals  hurried  or  retarded,  he  presses 
a  secret  key,  and  the  time  upon  all  the  dials  is  altered  to  suit  his 
convenience.  The  cook  finds  often  that  the  time  passes  very  rap- 
idly; while  a  quarter  of  an  hour  or  more,  not  otherwise  attainable, 
is  gained  by  M.  Houdin. 

"  Every  morning  this  clock  sends,  at  different  hours,  electric 
impulses  to  awaken  three  persons,  the  first  of  whom  is  the  gar- 
dener. But,  in  addition,  this  apparatus  forces  them  to  rise,  by  con- 
tinuing to  sound  until  the  circuit  is  broken  by  moving  a  small  key 
placed  at  the  farther  end  of  the  room.  To  do  this,  the  sleeper 
must  rise,  and  then  the  object  sought  is  accomplished. 

"The  poor  gardener  is  almost  tormented  by  this  electricity. 
The  greenhouse  is  so  arranged  that  he  cannot  raise  its  temperature 
above  50°  F.,  or  let  it  fall  below  37°  F.,  without  a  record  in  the 
study.  The  next  morning  Houdin  says  to  him,  '  Jean,  you  had  too 
much  heat  last  night;  you  will  scorch  my  geraniums ;'  or,  'Jean, 
you  are  in  danger  of  freezing  my  orange-trees;  the  thermometer 
descended  to  three  degrees  below  zero  (29°  F.)  last  night.'  Jean 
scratches  his  head,  and  says  nothing;  but  he  evidently  regards 
Houdin  as  a  sorcerer. 

"A  similar  thermo-electric  apparatus  placed  in  the  woodhouse 
gives  warning  of  the  first  beginning  of  an  incendiary  fire.  As  a 
protection  against  robbers,  all  the  doors  and  windows  of  the  house 
have  an  electric  attachment.  This  so  connects  them  with  the 
chimes,  that  the  bells  continue  to  sound  as  long  as  the  door  or 
window  remains  open.  During  the  day-time  the  electric  com- 
munication is  interrupted;  but  at  midnight,  the  hour  of  crime,  it 
is  re-established  by  the  study  clock.  When  the  owner  is  absent, 
however,  the  connection  is  permanent.  Then  the  opening  of  the 
door  or  window  causes  the  great  bell  to  sound  like  a  tocsin.  Every- 
body is  aroused,  and  the  robber  is  easily  captured. 

"  A  pistol-gallery  is  upon  the  grounds,  and  Houdin  often  amuses 
himself  in  shooting.  But  in  place  of  the  ordinary  methods  of 
announcing  a  successful  shot,  a  crown  of  laurels  is  caused  to  appear 
suddenly  above  the  head  of  the  marksman.  A  deep  road  passes 


OTHER  APPLICATIONS   OF  ELECTRICITY.      369 

through  the  park,  which  it  is  sometimes  necessary  to  cross.  On 
reaching  it,  no  bridge  is  to  be  seen;  but  upon  the  edge  of  the 
ravine  a  little  car  appears,  upon  which  the  person  desiring  to  cross 
places  himself.  No  sooner  is  he  seated  than  he  is  rapidly  trans- 
ported to  the  opposite  bank.  As  he  steps  out,  the  car  returns 
again  to  the  other  side.  This  being  a  double-acting  arrangement, 
the  same  aerial  method  is  made  use  of  in  returning. 

"  I  finish  here  my  description,"  says  Houdin.  "  Ought  I  not  to 
reserve  some  few  and  unexpected  details  for  the  visitor  who  comes 
to  raise  the  mysterious  knocker  below  which,  it  will  be  remem- 
bered, is  engraved  the  name  of  Robert  Houdin  ?  " 

Electricity  is  employed  in  timepieces  in  three  ways. 
Thus  it  is  made  use  of  as  a  motive-power,  to  swing  a 
pendulum,  and  replace  the  springs  or  weights  of  an  ordi- 
nary clock.  Or,  it  is  employed  for  transmission  :  a  cen- 
tral clock  sends  an  electric  current  every  second,  half- 
minute,  or  minute,  to  one  or  more  dials  placed  at  a 
distance,  which  cause  the  hands  to  advance  respectively 
a  second,  a  half-minute,  or  a  minute.  Or,  electricity  is 
used  to  regulate  clocks  and  dials  propelled  by  ordinary 
weights  and  springs,  and  adjusts  the  hands  every  hour, 
every  six  hours,  or  every  twenty- four  hours.  It  is  this 
system  of  synchronism  which  has  been  adopted  by  the 
city  of  Paris  for  the  public  clocks.  It  was  first  invented 
by  Dr.  Locke  of  Cincinnati  in  1848 ;  and  Congress 
awarded  him  a  premium  of  ten  thousand  dollars  for  his 
invention,  designing  to  use  it  in  astronomical  researches 
and  in  determining  longitude. 

Time-signals  are  now  transmitted  to  every  important  city 
and  to  all  railroads  in  Great  Britain,  from  the  Greenwich 
Observatory.  In  other  parts  of  Europe,  especially  in 
Germany  and  France,  electric  clocks  are  everywhere  used. 
In  Paris,  the  standard  clock  of  the  National  Observatory 
is  connected  by  special  lines  with  about  thirty  "horary 
centres."  At  these  points  are  placed  clocks,  the  pendu- 


370  THE  AGE   OF  ELECTRICITY. 

lums  of  which  are  continuously  controlled  by  impulses 
sent  every  second  from  the  observatory  ;  and  they,  in  their 
turn,  distribute  their  beats  to  numerous  stations  in  the 
vicinity.  The  whole  city  is  thus  supplied  with  time  uni- 
form and  correct  to  a  second. 

In  the  United  States,  time-signals  are  sent  from  the 
standard  clock  in  Cambridge  Observatory  to  many  sta- 
tions in  Boston,  and  at  intervals  are  transmitted  over 
the  telephone-lines.  Standard  time  is  also  marked  on  the 
tapes  of  the  stock-exchange  tickers.  From  the  National 
Observatory  in  Washington,  time-signals  are  sent  to  New 
York  ;  and  the  operator  at  this  station  despatches  the  cur- 
rent which  drops  the  time-ball  on  the  Western  Union  Tele- 
graph Building  in  the  metropolis,  two  hundred  and  forty 
miles  distant.  The  ball,  after  being  hoisted,  is  held  by  a 
simple  catch  mechanism  which  is  controlled  by  an  electro- 
magnet. At  the  moment  of  noon,  New- York  time,  the 
officer  in  charge  at  Washington  closes  the  circuit,  the  mag- 
net retracts  its  armature,  the  catch  is  slipped,  and  the  ball 
drops.  The  instant  the  ball  reaches  the  base  of  the  pole, 
the  fact  is  automatically  telegraphed  to  Washington. 
Owing  to  the  great  height  of  the  ball  when  raised,  it  is 
visible  for  many  miles  around ;  and  directly  or  indirectly 
the  clocks  and  watches  of  nearly  three  millions  of  people 
are  thereby  kept  from  straying  very  far  from  the  true 
time. 

In  referring  to  some  military  uses  of  electricity,  we  have 
mentioned  the  very  remarkable  apparatus  which  records 
minute  intervals  of  time.  This  is  the  electro-chronograph  ; 
and  by  its  aid  not  only  is  time  measured  with  wonderful 
exactitude,  but  by  its  recording  apparatus  it  enables  us  to 
note  the  precise  instant  when  an  event  occurs.  This  is  of 
great  value  to  astronomers  in  securing  a  record,  for  ex- 
ample, of  the  transit  of  a  heavenly  body  across  the  merid- 


OTHER  APPLICATIONS   OF  ELECTRICITY.      371 

ian  ;  for  the  observer  has  only  to  keep  his  eye  on  the 
object,  and  tap  with  his  finger  a  button  or  key  at  the 
proper  moments. 

Who,  in  his  youthful  days,  has  not  read  the  story  of 
Aladdin  and  that  wonderful  lamp  which  procured  such 
marvellous  things  for  its  lucky  owner?  The  fervid  ima- 
gination of  the  Oriental  romancer  fairly  runs  riot  in  de- 
scribing the  "forty  basins  of  massy  gold;"  and  the 
beautiful  slaves  "bearing  large  golden  basins  filled  with 
all  sorts  of  jewels,  each  basin  being  covered  with  a  silver 
stuff  embroidered  with  flowers  of  gold;"  and  the  gor- 
geous edifice  with  "  its  treasury  filled  with  bags  of  money, 
the  palace  with  the  most  costly  furniture,  and  the  stables 
with  the  finest  horses  in  the  world."  And  all  this  from 
the  happy  thought  of  a  thrifty  dame  to  rub  the  lamp  clean  ; 
for  it  is  only  when  the  lamp  is  rubbed,  that  the  "  genie  of 
gigantic  size"  appears,  and  the  feast  of  wonders  begins. 
No  doubt  we  think  in  our  boyish  wisdom,  that  such  things 
are  all  very  well  to  read  about,  and  a  great  many  times 
too  ;  but  of  course  we  know  that  such  marvels  are  not  to 
be  taken  in  sober  earnest. 

But,  O  reader  of  maturer  years,  did  not  a  "genie  of 
gigantic  size,"  whom  we  have  named  Electricity,  come  to 
us — if  not  at  the  rubbing  of  a  lamp,  certainly  at  the  rub- 
bing of  a  bit  of  amber?  And  what  did  Aladdin's  genie 
do  half  as  wonderful  as  ours  has  done?  If  Aladdin's 
sprite  could  transport  him  from  place  to  place,  cannot 
ours  do  as  much  for  us  ?  and  very  much  more,  for  it  can 
carry  our  very  thoughts,  even  our  spoken  words,  perhaps 
some  day  our  faces.  And  as  for  the  wealth  it  has  showered 
upon  us,  who  can  estimate  the  value  to  humanity  of  the 
telegraph  alone,  all  its  other  works  aside?  The  rash  re- 
quest to  seek  the  "roc's  egg  of  the  Caucasus  "  marked  a 


372  THE  AGE   OF  ELECTRICITY. 

limit  to  the  power  of  the  fabled  Afrite.  Who  will  set 
metes  and  bounds  to  the  new  power  and  potency  which 
comes  to  answer  our 

"best  pleasure:  be't  to  fly, 
To  swim,  to  dive  into  the  fire,  to  ride 
On  the  curled  clouds"  ? 

"It  maybe  said,"  writes  Priestley,  "that  there  is  a 
ne  plus  ultra  in  every  thing,  and  therefore  in  electricity. 
It  is  true,  but  what  reason  is  there  to  think  that  we  have 
arrived  at  it  ?  " 

And  to-day,  entering  as  we  are  upon  the  very  Age  of 
Electricity,  surrounded  on  all  sides  by  its  marvels,  famil- 
iar with  them  when  the  mere  fact  of  such  familiarity  in 
itself  surprises  us,  that  question  asked  one  hundred  and 
twenty  years  ago,  in  the  feeblest  infancy  of  the  science, 
is  as  unanswerable  now  as  then. 


INDEX. 


Academy,  French:  award  to 
Volta,  32;  to  Bell,  139;  refuses 
to  consider  Jobard's  lamp,  138; 
on  Crosse's  insects,  65. 

Acoustic  telephone,  276;  vibra- 
tions, 282. 

Accumulation  of  electricity  by 
animals,  30;  in  Leyden-jar,  15. 

Accumulator.  See  Secondary 
battery  and  Leyden-jar  and 
Auto-accumulator. 

Addison  refers  to  telegraph,  208. 

Air-pump,  Sprengel's,  140. 

Alarms,  electric,  362. 

Amber,  attraction  of,  8;  excita- 
tion of,  4;  legend  of,  2;  soul,  1. 

Ampere,  the,  40;  how  measured, 
41. 

Ampere,  Professor,  experiments, 
85;  galvanometer,  211. 

Ancients,  knowledge  of  elec- 
tricity, 5;  of  magnet,  69. 

Animals,  effects  of  electricity 
on,  16,  18,  24,  28,  58,  335. 

Annunciators,  362. 

Arago,  experiments  on  electro- 
magnet, 85. 

Arc,  incandescence,  system,  144. 

Arc  light.     See  Light,  electric. 

Arc,  voltaic,  130;  E.  M.  F.  of, 
132;  color,  131;  temperature, 
131. 


Armature,  81;  dynamo,  induc- 
tion in,  101;  polarized,  82; 
Siemens's,  109. 

Atmosphere,  magnetic,  68,  77. 

Atmospheric  battery,  60. 

Attraction,  magnetic,  72. 

Auto-accumulator,  60. 

Bacon,  Lord,  on  Gilbert's  dis- 
coveries. 7. 

Bain,  automatic  telegraph,  241. 

Balloons,  electric,  176,  180;  elec- 
tric lighting  of,  147. 

Barlow,  experiments  on  tele- 
graph, 212. 

Barnacles,  removing,  by  elec- 
tricity, 63. 

Bath,  electroplating,  195. 

Battery,  cost  of  motors  driven 
by,  165;  frog,  336;  galvanic, 
35;  heat,  207;  storage,  201; 
voltaic  cup,  32.  See  also  Gal- 
vanic cell. 

Beccaria,  experiments  on  animal 
electricity,  28. 

Bell,  electric,  170.  See  also 
Alarms. 

Bell,  Professor  A.  G.,  telephonic 
investigations,  291. 

Bevis,  Leyden-jar,  17. 

Blasting,  electric,  355. 

Boat,  electric,  160,  176. 
373 


374 


INDEX. 


Bonnelli  telegraph,  245. 

Bottle,  electric,  20. 

Bourbouze  electro-motor,  155. 

Bourseul,  suggestion  of  tele- 
phone, 277. 

Boy,  electric,  340. 

Boyle,  Robert,  electric  discov- 
eries, 8,  122. 

Boze,  beatification,  125;  electric 
martyrdom,  16;  invention  of 
prime  conductor,  13. 

Brard  carbon-burning  cell,  54. 

Brush  discharge,  the,  128. 

Brush  arc  light,  132;  dynamo, 
115;  secondary  battery,  206. 

Buckling  in  storage  cells,  206. 

Buffon,  experiments  with  light- 
ning, 23. 

Bunsen,  galvanic  cell,  52. 

Buoy,  electric  light,  147. 

Cabseus,  electric  discoveries,  8. 

Cable,  Atlantic,  249-256;  circuit 
of,  260;  first  suggestion  of,  249; 
picking  up,  253;  submarine, 
first,  248;  submarine,  construc- 
tion of,  256;  retardation  in, 
256;  telephoning  on,  310. 

Callaud,  galvanic  cell,  51. 

Candle,  electric,  145. 

Cannon,  firing  by  electricity,  346. 

Carbon,  burned  in  galvanic  cells, 
53;  burning  battery,  61;  ele- 
ments, 49;  filaments,  139;  in 
telephones,  306. 

Carlisle,  discovery  of  electrolysis, 
183. 

Carriages,  electric  lighting  of,  147. 

Cartridge,  electrolytic,  347. 

Case,  W.  E.,  heat  battery,  207; 
secondary  battery,  206. 


Casselli  telegraph,  245. 

Cavendish  on  lightning-rods,  26. 

Cell,  galvanic,  35.  See  Galvanic 
cell. 

Chronograph,  electric,  348,  370. 

Circuit,  35;  telegraphic,  227. 

Clavecin,  electrical,  358. 

Clocks,  electrical,  369. 

Coils,  magnetic  effect  of,  79; 
currents  in  92-101;  induc- 
tion, 325. 

Collinson,  Franklin's  letters  to, 
18,  22. 

Colt,  submarine  telegraph,  248. 

Commutator,  104. 

Compass,  mariner's,  70. 

Condenser,  31,  259;  telephone, 
308. 

Conduction,  discovery  of,  10. 

Conductors,  39;  prime,  13. 

Cotugno,  experiments,  30. 

Coulomb,  the,  40. 

Cowper,  telegraph,  246. 

Crookes,  experiments  with  high 
tension  electricity,  330. 

Crosse,  electric  insects,  64;  ex- 
periments with  lightning,  332. 

Cunreus,  experiments  with  Ley- 
den- jar,  15. 

Cures,  electric,  28,  30. 

Current,  magnetic  effect  of,  77; 
path  of,  in  cell,  45;  qualities 
of,  40. 

Currents,  alternating,  104;  dan- 
gerous, 341 ;  due  to  mechanical 
motion,  92. 

Daft,  electric  locomotive,  173. 
D'Alibard,     experiments     with 

lightning,  23. 
Dal  Negro,  electro-motor,  154. 


INDEX. 


375 


Daniell,  galvanic  cell,  50. 

Davenport,  electro-motor,  157. 

Davidson,  electric  locomotive, 
162. 

Davy,  Sir  H.  Discovery  of  arc 
light,  128;  electrolytic  produc- 
tion of  metals,  etc.,  187;  on 
protecting  vessels,  63. 

Death  by  electricity,  341. 

De  Moleyn's  electric  lamp,  136. 

De  la  Rue,  galvanic  battery,  59. 

De  Lor,  experiments  with  light- 
ning, 23. 

Depolarization  of  cells,  59. 

"  De  Sauty,"  250. 

Diamond,  electric  light  from,  122. 

Diplex  telegraph,  237. 

Discharges,  electric,  compared, 
57;  high  power,  325. 

Dolbear,  condenser  telephone, 
308. 

Drawbaugh,  telephonic  inven- 
tions. 302. 

Duchemen,  buoy  battery,  62. 

Dufay,  discoveries  of,  11. 

Duplex  telegraph,  236. 

Dyer,  telegraph,  216. 

Dynamic  electricity,  57. 

Dynamo,  the,  100;  and  battery 
compared,  98;  and  magneto- 
electric  machines  compared, 
100;  and  electro-motors  com- 
pared, 168;  Brush,  115;  direct 
current,  106;  Edison,  116;  effi- 
ciency of,  107;  Gramme,  106; 
operation  and  construction  of, 
112;  classification  of,  111;  Sie- 
mens, 108,  114;  Wilde,  110. 

Earth  batteries,  62;  for  electric 
lighting,  137. 


Earth  currents,  258;  return,  225. 

Eatables  as  galvanic  elements,  65. 

Edison,  automatic  telegraph,  243; 
chemical  telegraph,  308;  lamps, 
140;  microphone,  302;  phono- 
graph, 320;  quadruplex  tele- 
graph, 237;  railway  telegraph, 
269. 

Eel,  electric,  342. 

Electric  light.  See  Light,  elec- 
tric. 

Electricity,  35;  from  magnets, 
88;  medical  uses  of,  335;  of 
human  body,  338;  utilizations 
of,  333. 

Electrics,  7. 

Electrodes,  182;  in  telephones, 
306. 

Electro-generative  combustible, 
54. 

Electrolysis,  182;  Cruickshank's 
discoveries,  184;  Davy's  dis- 
coveries, 185;  delusions  con- 
cerning, 186;  discovery  of, 
182;  Faraday,  laws  of,  189; 
phenomena  of,  187;  Hitter's 
experiments,  184;  theory  of, 
190. 

Electrolyte,  35. 

Electro-magnet,  the,  68;  Am- 
pere's experiments,  £5;  Ara- 
go's  experiments,  85;  Henry's 
experiments,  86;  how  made, 
83;  Joule's,  84;  polarity  of,  80; 
strength  of,  84;  Sturgeon's,  86. 

Electro-metallurgy,  182;  Bird's 
discoveries,  192;  De  la  Rue's 
discoveries,  192;  claimants  of 
invention  of,  192. 

Electro-motive  force,  39;  of  gal- 
vanic cells,  52. 


376 


INDEX. 


Electro-motor,  152;  advantages 
of,  174;  Bourbouze's,  155;  cost 
of,  compared  Avith  galvanic 
batteries,  1(55;  Dal  Negro's, 
154;  Davenport's,  157;  effi- 
ciency of,  170;  first  rotary, 
150;  Froment's,  159;  Henry's, 
154;  McGawley's,  156;  princi- 
ples of,  153,  166. 

Electropborus,  the,  31. 

Electroplating,  192. 

Electro  therapeutics,  3,  5,  28,  30, 
335. 

Electrotyping,  193. 

Elements  in  galvanic  cell,  35. 

Elkingtons,  electroplating,  193. 

Engine,  electro-magnetic,  152. 

Everett,  E.,  oration  on  submarine 
telegraph,  247. 

Eye,  Siemens's  artificial,  316. 

Faraday,  discovery  of  laws  of 
electrolysis,  189;  on  magneto- 
electricity,  88;  Mayo's  im- 
promptu on,  89;  on  strength 
of  galvanic  cell,  58;  test  of 
Davenport's  motor,  158;  theory 
of  earth  return,  226;  vollam- 
eter,  200. 

Faure,  secondary  battery,  205. 

Feast,  Franklin's  electric,  19. 

Field,  Cyrus  W.,  account  of  re- 
gaining cable,  254. 

Field-magnets,  100;  of  force,  75. 

Filament,  carbon,  139. 

Fire,  electricity  supposed  to  be, 
50. 

Fireplaces,  electricity  in,  53. 

Foucault,  electric-light  regulator, 
129. 

Fountain,  electric,  150. 


Franklin,  early  telegraph  experi- 
ments, 209;  electric  feast,  19; 
explains  Leyden-jar,  19;  kite 
experiment,  21 ;  letters  to  Col- 
linson,  22;  on  George  III.,  26; 
theory  of  electricity,  19;  upsets 
Pivati's  tube  experiments,  339. 

Franklin  institute,  report  on  tele- 
graphs, 215. 

Frog's  legs,  electric  phenomena 
of,  28. 

Froment  electro-motor,  159. 

Fuse,  electric,  348. 

Galvani,  28,  31. 

Galvanic  battery,  and  boiler, 
and  dynamo  compared,  52; 
arrangement  of,  43;  largest, 
63. 

Galvanic  cell,  the,  41;  Bunsen's, 
52  ;  Callaud's,  51  ;  carbon 
burned  in,  53,  61;  Daniell's, 
50;  gravity,  51;  Grenet's,  59; 
Leclanche's,  49;  polarization 
of,  47,  58;  life  supposed  to  be 
generated  in,  64;  of  the  future, 
62;  resistance  on,  46;  Smee's, 
48;  strength  of  current  of,  58; 
water  analogy,  44;  work  of 
the,  43;  with  eatables  as  ele- 
ments, 65. 

Galvanic  cells,  electro-motive 
force  of,  52. 

Galvanism,  29. 

Galvanometer,  Thomson's,  261; 
poem  on,  263. 

Gas  battery,  59. 

Gas  lighting,  electric,  59. 

Gilbert,  "De  Magnete,"  7. 

Gnomon,  electric,  24. 

Gold  plating,  197. 


INDEX. 


377 


Gordon,  invents  cylinder  electric 

machine,  13. 
Gramme,  ring,  106. 
Gravesande  theory  of  electricity, 

10. 

Gravity,  galvanic  cell,  51. 
Gray,  Elisha,  liquid  telephone, 

300. 
Gray,   Stephen,  discoveries,  10, 

209. 
Great  Eastern,  laying  cable  by, 

254. 

Greeks,  knowledge  of  amber,  2. 
Grenet  galvanic  cell,  49. 
Grove  gas  battery,  59;  galvanic 

cell,  161. 

Guericke,  Von,  discovery  of  elec- 
tric repulsion,  8 ;  produces 

electric  light,  122. 
Gummert,  discovery  of  electric 

light  in  vacua,  127. 

Hair,  effect  of  electricity  on,  9. 

Harmonic  telegraph,  238. 

Hawkesbee,  electric  machine,  15; 
experiments  on  electric  light, 
124. 

Heat  battery,  Case's,  188. 

Henry,  Joseph,  experiments  on 
electro -magnet,  86;  on  elec- 
tro-motors, 154;  on  telegraph, 
212. 

Houdin,  electric  alarms,  305. 

Hughes,  Professor,  induction 
balance,  314;  microphone,  300; 
sonometer,  314. 

Incandescence  arc  system,  144. 
Incandescent  electric  lamps,  136. 
Incubator,  electric,  363. 
Induction    balance,    314;    coils, 


306,    326,    329;    in    telephone 
lines,  309;  magnetic,  72. 

Insulation,  discovery  of,  11. 

Insulators,  39,  248. 

Insects,  electrical,  Crosse's,  64. 

Jablochkoff,  atmospheric  bat- 
tery, 60;  auto-accumulator,  60; 
candle,  145;  carbon-burning 
cell,  53. 

Jack,  electric,  20. 

Jacobi,  discoveries  in  electro- 
metallurgy, 192;  electric  boat, 
160. 

Jamin,  magnet,  86. 

Jenkin,  telpherage,  177. 

Jordan,  discoveries  in  electro- 
metallurgy, 192. 

Killing  of  animals  by  shocks,  18. 

Kite,  Franklin's,  21. 

Kleist,  von,  discovery  of  Leyden- 

jar,  15. 
Kendall,  carbon  battery,  61. 

Lamp,  electric,  Foucault's  regu- 
lator, 129;  Brush's,  132;  Sie- 
mens's,  133;  Soleil,  146;  De  la 
Rue's,  138;  incandescence  arc, 
144;  incandescent,  136;  incan- 
descent distribution  of  current 
in,  143;  duration  of,  151;  in- 
candescent, Edison's,  142;  in- 
candescent, Jobard's,  138  ; 
incandescent,  construction  of, 
139;  incandescent,  Muthel's, 
143;  incandescent,  Swan's,  142; 
incandescent,  surgical,  148. 

Launching  by  electricity,  356. 

Laws  of  electricity,  35. 

Leyden-jar,  15. 


378 


INDEX. 


Light,  conversion  of  electricity 
into,  119. 

Light,  electric,  applications  of, 
146;  arc,  128;  at  sea,  356; 
Boze's,  126;  by  earth  batteries, 
137;  candle,  145;  cost  of,  151; 
distribution  of  current,  143; 
early  modes  of  producing,  122; 
economy  of,  151;  Edison's  ex- 
periments, 140;  first  from  gal- 
vanic current,  128;  from  dia- 
mond, 122  ;  genesis  of,  8  ; 
Hawksbee's  experiments,  122; 
incandescence  arc,  144;  incan- 
descent, 136  ;  influence  on 
vegetation,  150;  in  lighthouses, 
135;  in  vacuo,  127;  from  mer- 
cury jet,  123;  photographs  by, 
129;  spark,  146;  statistics  of, 
151 ;  theatrical  effects  by,  130, 
149;  theory  of,  120;  towers  for, 
137;  Wake's  experiments,  124. 

Lightning,  electro-motive  force 
of,  59;  fusing  metals  by,  332; 
identity  with  electricity,  9,  21 ; 
rods,  25. 

Loadstone,  70. 

Locomotive,  electric,  Daft's,  173; 
Davidson's,  162;  Hall's,  163; 
Lillie's,  163;  of  1845,  162; 
Page's,  163  ;  Siemens' s,  171  ; 
Sprague's,  174. 

Lyncurium,  5. 

Lyre,  Wheatstone's,  275. 

Machine,  frictional  electric,  12, 
58,  325. 

Magnet,  currents  produced  by,  88 ; 
Geilbert  on  the,  7;  Jamin's, 
86;  Newton's,  86;  origin  of 
the,  69;  permanent  and  elec- 


tro, compared,  80;  strength  of 
86. 

Magnetic  motors,  71. 

Magnetism  and  electricity,  iden- 
tity of,  33;  conversion  of,  68; 
known  to  ancients,  3. 

Magnetization,  85. 

Magneto-electricity,  88-96. 

Magneto-electric  machines,  90- 
112. 

Magneto-induction,  94. 

Medicine,  electricity  in,  28,  30, 
335. 

Microphone,  300. 

Middlings-purifier,  electric,  331. 

Mines,  electricity  in,  148,  348. 

Minus  electricity,  19. 

Morse,  S.  F.  B.,  217,  248. 

Motion,  converted  into  electri- 
city, 97;  transmitting,  272. 

Motors.     See  Electro-motors. 

Motors,  magnetic,  71-164. 

Music,  electric,  358. 

Needle  telegraph,  224. 

Needling,  206. 

Negative  electricity,  11. 

Newton,  Sir  I.,  magnet,  86;  elec- 
tric discoveries,  8. 

Nicholson,  discovery  of  electro- 
lysis, 183. 

Nickel-plating,  196. 

Nobili,  rings,  189. 

Nollet,  Abbe,  18,  20,  25. 

Ocean,  in  galvanic  cell,  62. 
Odor,  electrical,  336. 
Oersted,  33. 

Ohm,  the,  40;  laws  of,  39;  stand- 
ard, 40. 
Organ,  electric,  358, 


INDEX. 


379 


Pacenotti,  ring,  160. 

Page,  Professor,  electro-music, 
277;  electric  locomotive,  163. 

Peltier  effect,  56. 

Phonograph,  the,  320. 

Phosphorus,  mercurial,  123. 

Photophone,  the,  314. 

Photographs  by  electric  light, 
129-148. 

Piano,  electric,  358. 

Pile,  voltaic,  31 ;  Zamboni's,  63. 

Pixii,  magneto-electric  machine, 
90. 

Planta,  electric  machine  of,  13. 

Plante,  secondary  cell,  204. 

Plants,  effect  of  electricity  on, 
150. 

Plus  electricity,  19. 

Potential,  electric,  36. 

Polarity  of  compass,  8;  of  mag- 
nets, 71. 

Polarization  of  cells,  47. 

Poles,  magnetic,  71. 

Positive  electricity,  11. 

Raia  torpedo,  342. 

Railway,  electric,  Daft,  173 ; 
Hall's,  163;  Lillie's,  163;  in 
United  States,  173;  of  1845, 
162;  Siemens' s,  171 ;  Sprague's, 
174. 

Railway  signals,  electric,  357. 

Railway  telegraphs,  267. 

Railway  telepherage,  179. 

Recording  telegraph,  229. 

Refining,  electro,  197. 

Regulator,  Foucault's,  129. 

Reis,  telephone  investigations, 
280. 

Relay,  telegraph,  232. 

Repeater,  telegraph,  234. 


Repulsion,  electrical,  8. 
Resinous  electricity,  11. 
Resistance,  39;  interval  of  cells, 

46. 

Retardation  in  cables,  256. 
Reynier,  secondary  battery,  205. 
Ronalds,  telegraph,  210. 
Royal  Society  criticises  Franklin, 

22;  refuses  recognition  of  Boze, 

127. 

Rechmann,  death  of,  24. 
Ritter,    electrolytic    discoveries, 

184,  203. 

Sauer,  sunlight  cell,  66. 

Schulze,  Professor,  on  Crosse 
insects,  65. 

Secondary  battery,  201 ;  Brush's, 
206;  Case's,  206;  defects  of, 
206;  Faure's,  205;  Plante's, 
204;  Sellon's,  206  ;  Reynier' s, 
205. 

Seebeck,  discovery  of  thermopile, 
55. 

Sellon  secondary  battery,  206. 

Ships,  electric  lighting  of,  147. 

Shocks  from  Leyden-jar,  18. 

Siemens  arc  light,  133;  amateur, 
110;  artificial  eye,  316;  dy- 
namo, 108;  electric  locomotive, 
171;  submarine  cable,  248. 

Sight,  electric,  347. 

Signals,  railway,  electric,  357. 

Silk,  discovery  of,  as  insulator, 
11. 

Siphon  recorder,  261. 

Scemmering,  telegraph,  210. 

Soleil  light,  146. 

Solokow,  25. 

Sonometer,  Hughes',  314. 

Sound    from    magnets,    Page's 


380 


INDEX. 


discovery,  277  ;  transmitted 
through  solids,  274;  vibrations, 
273;  wave  motion,  282. 

Sounder,  telegraph,  230. 

Spark,  electric  light,  146. 

Spencer,  electro,  metallic  discov- 
eries, 192. 

Spectra,  magnetic,  73. 

Sprague,  electric  locomotive,  174. 

Sprengel,  air-pump,  140. 

Starr,  incandescent  lamp,  136. 

Static  electricity,  57. 

Static-electric  machines,  325. 

Statues,  electrotyping,  194. 

"Steams,"  electrical,  10. 

Steering,  electrical,  356. 

Storage  of  electricity,  199. 

Strada,  refers  to  telegraph,  208. 

Strength  of  current,  41. 

Sturgeon,  electro-magnets,  86. 

Sulzer,  discovery  of  electric  ef- 
fects of  metals,  30. 

Sulphur-globe  electric  machine, 
8. 

Sunlight  cell,  66. 

Sun,  electric,  147. 

Swan  incandescent  lamp,  142. 

Taste,  electrical,  30,  336. 

Telegraph,  Ampere's,  211;  auto- 
graphic, 245;  automatic,  241; 
Barlow's  experiments,  212;  di- 
plex,237;  duplex,  236;  Dyer's, 
216;  early  experiments,  208; 
Edison's,  243 ;  electro-mag- 
netic, invention  of,  221;  first 
in  Europe,  223;  first  in  United 
States,  219;  Franklin  institu- 
tion report  on,  215;  harmonic, 
237,  290;  Henry's,  212;  Lom- 
ond's, 210;  Lover's,  276;  mili- 


tary, 354;  Morse's,  217;  multi- 
ple, .237;  principles  of,  225; 
printing,  243;  railway,  267; 
Reizen's,  210;  recording,  229; 
relay,  232;  repeater,  234;  sig- 
nals, 230;  Ronald's,  210;  Stem- 
mering's,  210;  submarine,  247; 
system,  232;  Trebouillet's,  222; 
Vail's,  272;  Wheatstone's,  223; 
wires,  length  of,  270;  writing, 
246. 

Telegraphing,  long  distance,  234. 

Telephone,  the,  272 ;  balloon,  307 ; 
Bell's,  291-295;  Bourseul's  sug- 
gestion, 277;  chemical,  Edi- 
son's, 307  ;  condenser,  308  ; 
current,  309;  Drawbaugh's  in- 
ventions, 302;  friction,  Bell's, 
306;  Gray's,  290;  in  theatres, 
313 ;  liquid,  300 ;  magneto, 
principles  of,  296  ;  military 
uses  of,  354;  odd  uses  of,  316; 
patent,  Bell's,  297;  receiver, 
296;  records,  315;  Reis's,  280; 
resistance,  principles  of,  298; 
system,  Van  Rysselberghe's, 
313;  transmitter,  Benjamin's, 
305;  transmitter,  Blake's,  303; 
transmitter,  Drawbaugh's,  304; 
undulatory  current,  theory  of, 
297. 

Telephoning,  at  sea,  311  ;  by 
earth's  magnetism,  306;  long 
distance,  312;  without  wires, 
312. 

Telephotograph,  264. 

Telpherage,  177. 

Theatres,  electric  light  in,  130. 

Theories  of  electricity,  10,  19,  28, 
29,  31,  35. 

Thermo-electric  battery,  55. 


INDEX. 


381 


Thermo-galvanic  cell,  54,  207. 
Thermopile,  the,  55. 
Thompson,  effect,  the,  56. 
Thomson,  spark  light,  146. 
Ticker,  telegraph,  244. 
Timbre,  282. 
Time  by  electricity,  369. 
"Torpedo,"  the,  5,  342. 
Torpedo,  electrical,  352. 
Tourmaline,  electricity  of,  5. 
Towers,  electric  light,  137,  147. 
Transmission  of  power,  175. 
Trebouillet,  telegraph,  222. 
Tricycles,  electric,  176. 
Tubes,  Pivati's,  339. 

Undulatory     current     in     tele- 
phones, 297. 

Vacuum,   magnetic    effects    in, 

97. 
Vacuum    tubes,    electricity    in, 

127,  330. 
Van     Rysselberghe,     telephone 

system,  313. 
Vegetation,  effect  of  electric  light 

on,  150. 

Velocity  of  electric  discharge,  18. 
Vessels,  protecting  by  galvanic 

action,  63. 

Vestal  fire,  electrical,  3. 
Vitreous  electricity,  11. 
Volta,  Alessandro,  31;  letter  to 

Banks,  182. 
Voltaic  arc,  128. 
Voltaic  cell,  48. 


Voltaic  pile,  31;  duration  of,  63: 
electrolysis  by,  183;  secondary, 
203. 

Voltameter,  200. 

Volt,  the,  40. 

Wall,  Dr.,  notes  identity  of  amber 
sparks  and  lightning,  9. 

War,  applications  of  electricity 
to,  346. 

Water,  electrolysis  of,  58,  183. 

Watson,  Dr.,  early  telegraph  ex- 
periments, 18,  209;  exposes 
Boze,  126;  on  lightning-rods, 
26. 

Weekes,  electric  lighting  towers, 
137. 

Whales,  killing  by  electricity, 
341. 

Wheatstone,  automatic  tele- 
graph, 241. 

Wheatstone  and  Cooke,  tele- 
graph, 222. 

Wheatstone,  Sir  C.,  magic  lyre, 
275. 

Winkler,  on  Leyden-jar,  16;  on 
glass  globe  machine,  13. 

Wire,  electroplating,  198. 

Work,  electrical,  37. 

Wright  and  Bain,  railroad  tele- 
graph, 268. 

Wright,  discoveries  in  electro- 
plating, 193. 

Zamboni,  dry  pile,  63. 

Zinc,  consumption  of,  in  cells,  53. 


FROM  A  LEADING  MASSACHUSETTS  TEACHER. 

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